What do you like to play against the Catalan as Black?

Can't help you there - I avoid it as Black.  Guess you need to find QGD and Nimzo-Indian players.

I don't like to play against the catalan as black either. But with the white pieces, I find early dxc4 lines very annoying. (which is why I play a reti move order)

To me, the Reti is no good unless it is transposed into via the English.

The Reti proper, which is 1.Nf3 d5 2.c4, to me is a problem because of 2...d4!  I only see the Reti working when Black has to play ...c6 or ...e6 first, like is often the case in the English Opening.

For example, 1.c4 e6 2.Nd3 d5.  Now 3...d4 is not nearly an issue as Black will have to waste a move to get the pawn to ...e5.

But after 1.Nf3 d5, I see 2.d4 as the only move, intending 3.c4, leading to a Queen's Gambit or Catalan.

There is quite a lot of posts already in the forum on the subject. Play maybe the most main line myself with be7, 0.0 then d5xc4. There was a recent Carlsen v Nepo world championship game with the trendy b5 against Qc2. There is nothing wrong with the old ..a6 instead, white has to be a very good technical player to get anywhere in this line.  Also b6 is a exchange sac idea, black getting quite good play after Ne5, Qxd4 QxR QxN.

An early d5xc4 followed by a6 is quite trendy. 

I play the Slav which avoids the Catalan but you can still face the setup. I would recommend checking out my Classical Slav Study where I do cover the Catalan Setup against the Slav. I will also give you a link to my Semi-Slav Study where you can face the Catalan Setup but with a knight on c3. You may also want to see my 1.d4 Sidelines Study so you can better handle d4 openings like the London which you struggle against

The reason I think you have with the Catalan is that you like the Queen's Gambit Accepted which if they play 1.d4 and 2.Nf3, they completely avoid it until they eventually push c4 which at that point you are in their territory. I think knowing a little bit of the Slav will help you as ...dxc4 is a thematic move in the opening.

With your Queen's Gambit Accepted, may I suggest an improvement?

If you are aiming for an opening advantage, I am inclined to agree with you. But I’ve never been very concerned about getting an opening advantage with the white pieces- I’d rather play into a familiar position to minimize my opening study so I can focus on other aspects of my game.

How does 1.Nf3 minimize opening study?

1...d5 - Here you have a choice of 2.c4, 2.d4, or 2.g3.  Obviously you only need to know one of them.

1...e6 - This can lead to Reti setups, Dutch setups, or English Defense or Hedgehog setups

1...f5 - Anybody that plays the Dutch against 1.d4 will often play this - This is my main response to 1.Nf3 or 1.c4.  Against 1.d4, I play 1...e6 first.

1...b6

1...Nf6 - A very flexible response for Black - Can lead to almost any structure

1...g6 - Modern Defense players can pretty much play this against any first move except 1.b3 or 1.b4.

Playing 1.Nf3 is no less complicated than playing 1.e4 or 1.d4.  In fact, what I play now, 1.b4, has far less theory than 1.Nf3.  When it comes to opening study, 90% of it for me is Black.

I used to play 1.b4 back in 2008-2009 and 2014.  Since switching back to 1.b4 in May, I actually looked and I have played 26 games as White since then if you Exclude Blitz games over the board.  I have 19 wins, 3 losses, and 4 draws.  If you include the 2 blitz tournaments I've played in, add 7 more to the wins.  7 and 0.  In fact, White has a very strong record in those 2 blitz events.  In one, it was a 4 round event where you play Black and White against each player (8 games).  White went 6-2, with me winning all 4 of my games with White and finishing with a score of 6 out of 8.  In the second one, it was a 6-rounder, just 1 game each round, and White went 6-0 (myself of course scoring 3-3).

So if you want something strong with little theory, give 1.b4 a look.  In 33 over the board games if you include Blitz, I don't think you can complain about winning 26 of them and drawing 4 of the other 7!

I already know a decent amount of KID fianchetto theory, as well as fianchetto benoni theory (I score very well with them otb as well - I don't think I've lost a game as white vs the KID or benoni)

I'm very comfortable with playing the english opening structures, so I choose not to study theory there. 

I don't know dutch theory, and admittedly I score the worst against the dutch (my two dutch otb games ended in a draws against slightly lower rated opponets). But as long as I use my time in the opening I can get, at minimum, an acceptable position, and I just play chess from there. 

As for the other, more obscure lines, like b6 and g6... I simply just play chess. It's not a critical line, so therefore as long as I keep an open mind to transpositions and pawn structure I can do well against them.

Basically, I Already know the necessary theory for the critical lines, and for the rest, I don't need to study the lines in order to play out an acceptable position.

I mean, I score well enough =)

On a side note, I did play 1.b4 in an OTB game.

It was in Memphis, and the Memphis chess club had a play 1.b4! by Lapshun. It was a 3-day tournament, so for the first few rounds I got to the club ahead of time to simply read the book. In round 3 (last day of day 2) I got the brilliant idea to play 1.b4 against my 1800 rated opponent (I was 1960). I ended up getting a mediocre position out of the opening (like I usually do) but after some defense I ended up winning in the endgame. Partly because my opponent was in time pressure and had to make it to move 40 quickly.

I'm sure you can see my unfamiliarity through my opening play lol. Time control was 90+30 SD 30 I believe.

If White does g3 early as below, I'd suggest trying to switch to a Catalan, though if white does not play d5, I think it ends up as an English opening

If on the other hand black plays d5 early like I do, then I'd usually do a Slav setup as a couple have mentioned above.

Here's some of my more interesting ones between May and now.  And actually, I was wrong with the numbers.  One game, I played 1.e4, and lost, in that stretch.  It's actually 19 wins (26 if you count blitz), only 2 losses, and 4 draws, in 25 games (32 if you include blitz).

What I like so much about 1.b4 is the chaos it can create.  The first 2 games here were total chaos, and the fourth I would consider my best of the 19 wins:

Black is winning in the first one, until she blunders badly and suddenly White is winning!

Here was another chaotic game.  He completely missed the idea on move 21, allowing White's 22nd move.

This one is a complete demolition - a miniature against an 1800 player

This is my favorite of the 19 wins:

And it wouldn't be complete without this utter piece of chaos played earlier this month:

in the diagram you posted, it can also transpose into a modern benoni, fianchetto if white pushes d5. 

I do enjoy the chaos, but the main reason I don't play it is because I Can't ever properly judge the positions. I like chaos if I can make sense of it and my opponent can't, but I'm generally a pretty cautious person so I simply stick with what I know.

On the other hand, maybe this is a bad time to let you know I played you once in a blitz game (otb) before...? You did play 1.b4 lol

Oh, really?  Where at?  Was it this year in Charlotte(June) or Charlottesville(July)?  Or was it a while back when I played b4 in 2008, 2009, or 2014?

No... in 2008 I would have been 4 years old haha.

It was last year NCC (June?) blitz event, first round. I remember the ending pretty vividly. I gave a check with my queen because I was panicking, and you moved your king, and I didn't know what to do so I looked around, and saw that I could take your queen with my queen. For free. Basically, we both hung our queens. 

Oh, NCC as in North Carolina Closed?  If so, that was October.  I may have played 1.b4 in the blitz event.  The slower main event I was playing 1.e4.  I recall a chaotic draw in a Closed Sicilian, not sure what the other White opening was.  I started that event with Black and I think I had 3 Blacks.  I did also play 1.b4 maybe 2 or 3 times a year between 2015 and 2021 in slow games, but it was mostly 1.Nf3 (i.e. 2018), 1.d4 (2019 - Torre and Colle), or 1.e4 (July 2020 after the Pandemic shutdown thru May 2022).

No it was the North carolinas classic. I lost maybe 20 rating points that tournament? I was top seed of my section, too. After that event my dad banned me from playing out of state unless it was tennessee lol. I only did well in the blitz event.

nice that you guys met

If your father is banning you because of a bad result out of state, he's an idiot!  About as bad as those little league moms that yell at their sons for failure, whether it be striking out as a hitter or allowing a home run as a pitcher.

He needs to get a clue that you will lose games.  You will have bad tournaments.  Everyone does, myself included!

You need to tell him that you need to go back to North Carolina.  NC Open is Thanksgiving weekend.  Charlotte Open is Martin Luther King weekend.  Carolinas Classic is in June.  You are not eligible for the NC Closed unless you live in NC or attend college in NC.  That is in 2 weeks.