This free course on Chessable "Short & Sweet: Sielecki's Queen's Gambit Declined" really helped me out against d4!
https://www.chessable.com/short-sweet-sieleckis-queens-gambit-declined/course/95878/
But as every other chess.com member will now go on to say.... it doesn't matter what you are doing in the opening if you aren't following the basics of good chess principles. Make that a priority too
https://www.youtube.com/watch?v=Ao9iOeK_jvU&list=PLl9uuRYQ-6MBwqkmwT42l1fI7Z0bYuwwO&index=6
At your rating surely just protect your pieces and wait for opportunities? Pretty sure that's the general consensus, I've not studied openings, just avoiding blunders. 👍
Plus I'm floating between 20 minute and 30 minute games, gives time to think. May help
#1
"I jump between ~350 to 450 rating" ++ check for blunders before you play
"with 10 minute time controls" ++ change to 15|10
"I play The Italian, working on queens gambit" ++ Both are good, pick one and stick to it.
"then for black I play the french and feel comfortable playing the sicillian dragon"
++ Both are good, pick one and stick to it.
"i'm gonna need a opening that works for 1 d4" ++ Queen's Gambit Declined, Queen's Gambit Accepted, Slav Defence, all good. Pick one and stick to it.
"everything I have attempted feels uncomfortable and off" ++ Your feeling is off.
tygxc. I think what you have just suggested is very telling. Playing a longer time control to give me time to actually play the best I can in every situation. Rather than mediocrely or below mediocrely playing multiple openings just have 3 that I need to have to adress what I will face. 
I'm already pretty comfortable with Italian, French and i'll need to find one for D4 that gives me something to work towards!
Thank you!
Play e6, d5, c5 and likely you will transpose to a French position/Sicilian since most players will go d4, e4.
My 2300 USCF coach plays this line being he is a French and E6 Sicilian player himself.
Personally, I play the Grunfeld or Indian Game hybrid because I like the imbalance , ambition and dynamics.
I like the Semi-Slav but it takes some practice to get the hang off. Here is a quick pgn
Here is my Semi-Slav study but I would recommend you don't focus too much on all the side variations. This is a Grandmaster Repertoire so try to understand how the opening relates to the middlegame and you will be fine. It doesn't cover the calmer variations against Bg5 but there are plenty of resources to help
Chapter 5 is my Winawer Countergambit prep if you want to look at that
Thank you guys for all the advice I really appreciate it!
I've taken a look at the Queens Gambit Declined and it basically is the French which works well for me cause I already play the French so I can develop greater positional understanding around the French by playing that and strengthen my play that way.
I've long considered the Dutch as well, my problem with learning the Dutch is that at my rating I encounter E4 or other variations far more than D4 and therefore don't get much practice at defending against D4 openings. So I learn the Dutch the quickly forget it due to lack of repetition of practice for it.
Either way, i'm happy I have resources to work towards. I'm playing 10min time controlled games mostly but interweving 15/10 time controls for slower more learning oriented games. I'm then going back after a string of games or the day after and looking at the games and taking away a few things.
1. What did I do that worked well?
2. What did I struggle against and what can I do about it?
3. What tactical ideas were used and do I understand how they worked?
4. When trading especially in complicated positions, did I trade either for piece value advantage or for a positional advantage?
5. What were my attacking ideas, what were my opponents?
6. Endgame. What opportunities for mate did I utilize, what alternatives could I have attempted that might have led to mate.
7. I think mostly importantly. Where were the weaknesses in my position could they have been reinforced, or played around better?
Hey guys, i'm a beginner to chess. I've played a reasonable amount of chess to have the basics mostly down and I have an understanding of what I need to work on if I wish to improve. I jump between ~350 to 450 rating with 10 minute time controls. I play The Italian, working on queens gambit, then for black I play the french and feel comfortable playing the sicillian dragon. But I if I want to improve i'm gonna need a opening that works for 1 d4. I'm not really sure what to pick as everything I have attempted feels uncomfortable and off. Any advice or suggestions would be greatly appreciated!
Thank You!