I have been studying chess for a solid 6 months now, but I can't progress past 1400

I agree on playing longer games.  But anyways, improvement in chess doesn't tend to be especially gradual.  You can be stuck in a rating range for a while and then shoot up 150 more points.

If you really want to improve, find a chess club you can go in person to, and if the stronger players are willing to go over the games with you afterwards, take advantage.  

Try your own hand at analysis as well.  That first game includes both blunders and some real positional mistakes you could learn from.  I'd analysis, post it in a separate post with your analysis, and ask for guidance on the game.  

Edit:  actually, the second game is much the same.  Both parts of your game could use a little work -- positional knowledge, and blunder prevention.  You can gain some points just from absorbing the fundamentals, since I'm seeing easy to fix mistakes like castling into airy & hard to defend positions.

You're playing London System, but you can't really handle it. For instance here your opponent wants to exchange your strong blacksquared bishop and you let him do it. Also your light-squared bishop doesn't feel good on d3 square in King's side fianchetto systems e. g. King's Indian Defense, Grunfeld and etc:

So the point of playing h3 is to create a safe square for your bishop on h2 and if your opponent goes for it then you play Bh2.

Overall your main problem is that you don't have essential strategical and endgame knowledge. If you are interested in coaching - then I can be your coach. But if you want to study by your own I can suggest reading "My system" by Aron Nimzowitsch.

Thanks for the advice! Indeed, I pushed h3 to create an escape square for my bishop but eventually thought it would be awkward to retreat my bishop to h2 especially if my opponent would castle king's side. So I figured I'd rather have a semi open file for my rook after castling. What could have been a good developing strategy after Bh2?

Also thanks for your offer, but I think it's best for me to read into theory right now. I will definitely pick up a book sometime later!

Indeed, I pushed h3 to create an escape square for my bishop but eventually thought it would be awkward to retreat my bishop to h2 especially if my opponent would castle king's side.

In the most cases it's usually a good idea to keep your black-squared bishop in the London System. I think only in the Dutch Stonewall (probably in the Chigorin also, but I'm not sure) it's possible to leave the bishop on f4 in order to open the e-file - then e6 becomes a serious weakness.

So I figured I'd rather have a semi open file for my rook after castling.

You have already pushed your c-pawn to c4. It means your queen's side isn't really safe for your king anymore. By pushing c-pawn you're showing that you are going to castle to the king's side and try to attack on the queen's side. It's actually the main idea for White in the King's Indian Defense (in general)

What could have been a good developing strategy after Bh2?

The classical set up like Nf3, O-O, Nc3, Rb1, b4 looks pretty decent here.

By the way if you want to play opposite side castling games then you can transpose into Pirc Defense by playing moves like this:

I had a draw against a grandmaster (definitely not a strong one but anyway ) in this opening:

https://www.chess.com/live/game/4458008443

Also thanks for your offer, but I think it's best for me to read into theory right now. I will definitely pick up a book sometime later!

I don't think that you need to focus on opening at the moment, because first you need to learn essential chess strategy - otherwise you'll be not capable of taking an advantage of your opponent's opening mistakes. Like all your hard work isn't going to work for you. I suggest focusing on strategy, analyzing annotated games (classics) and tactics of course.

The best way to improve is to go into a chess club.

Not a virtual one like chess.com,, at least it is not enough.

There, u could play games and analyze with stronger opponents who will give you advices.

That's better than playing only online and for example looking at engine's analysis which doesn't explain.

I guess you can find it near u a chess club in Netherlands.

Not everyone has time to go to a chess club on a regular basis. For 1000-2000 elo it's great, but after that only books, Chess Base, personal coach and OTB games.

my answer was of course for the person asking, so for low level players.

Studying chess asks time anyway. U don't have time? Well, don't expect to improve quickly...

Hi, 

First of all, 6 mounth to get 1300 on chess.com is good. I played chess for 3 years, and I find 1300-1400 players here quite hard, perseverant and experienced (1300 is probably 1500 at least on other sites or in FIDE level). Even with a piece down, they tried to push for the win with dangerous threats, like vicious past pawns or other stuffs. 

As you play london system, you can take a look at gingerGM's playlist on youtube, there are 4 videos on how to play it against the main black setups (look at London System, not Jobava London which is different and weaker to my mind - Jobava setup, with Nc3 without c4 is good if black plays g6 and fianchetto kingside, but in other lines, it's less playable than Nbd2) :

https://www.youtube.com/playlist?list=PLQQ6Y41L8gPORQso4EvXLP6ucQUadXeUm

If you want more, on London System, I have also some studies in PGN (contact me by private message to get it if you want).

He only played 11 games at the time of writing. 7 rapid and 4 blitz. Nothing wrong with 15/10 rapid games. I hold it as a minimum. Sure, longer is even more preferable. But stay away from blitz untill you get better. And if you're really serious about playing chess, then it is definitely advisable to join a club like @poucin said.

1400 after only six months is excellent. Were you expecting to become a GM after that time?

A culprit:

Puzzles

Stop all that business (except for occasional entertainment) and play your game. You have fallen into the standard hype ... "chess is all about tactics." For starting players, your efforts are being wasted, the energy is far better served elsewhere. 

Puzzle solving is about finding a solution, that a single move leads to victory or saves the draw. Such positions are few and far between in any given game. Besides, these are positions reached by other players, possibly understood by them. They are not representative of your games. Looking at every move as if it were a puzzle to be solved and ur no longer playing chess.

you should learn lines

You need to practice longer. I've been doing it for years, yet my highest was around 620.

get in some daily chess tournaments with players just above your level. If you are a blitz player get 50 or so games going. it will force you to slow down while still giving you the action you desire.

https://www.chess.com/tournament/daily-3-day-tourney-200-ply

https://www.chess.com/tournaments/all?type=upcoming&sort=start_date

You played a few games and you think that your target is to pass 1400? You need about 30 games to see where you are. Your estimation might be way off. I am telling you this to save you from further frustration since most of us were thinking the same way when we started. The only thing that is somewhat reassuring is the 23 you have in 5mins puzzle rush, which I consider somewhat normal for someone between 1100-1300 (in blitz).

It is not so easy for molst players to raise their ratimgds--this is becasuie most players make ther same errors over and over and do not realize this.

That's why u need to receive advice and analysis from stronger players, thus going into a chess club.