Which level did you get stuck?

I remember finding it quite difficult to reach 1600 ... Then 2000.

Now I'm finding it difficult to reach 2500, though that's probably because life is busy these days, and I don't have as much time to devote to chess as I used to.

My process is the same for every level: playing a lot of games, and trying hard to learn from every loss.

Lost games are the secret to improving, because they highlight the mistakes in your play that you need to fix ...

I was stuck between 900-1000 and before that I was 1200 (wasn't really the level so I lost 200 points haha) and I studied the Caro Kann and the Queens Gambit (Then Sicillian) and also watched some videos about the middlegame and endgame, and started learning tactics, and I finally reached over 1100, and now I am 1400 ^^

I don’t really count online since by the time internet chess was a major thing I had probably already finished improving / putting effort in but I did have plateaus in OTB chess. 
Each time the solution was the same - I just had to play much stronger players. So I would go to tournaments and look to play in the highest section possible (and I mean the absolute highest, usually a strong open) where I was guaranteed to be facing better players in almost every game.

Sometimes I would have post-game analysis with some of these guys and get insights.

Then I tried to figure out what I was doing wrong, going over all my games, looking up my openings, asking myself why this, why that, and eventually I was able to get to somewhat decent level.

In short you have to lose lots of games vs good players and try to see what is happening.

heh now's probably the time to tilt :/