I'm always around 1050-1150 but can't seem to break out.
I do a lot of puzzles, i review my games and constantly think about undefended pieces of possible blunders.
Now blunders are more rare than regular and most of the time now i feel like i'm losing because i just get crushed by tactics.
I feel like i'm a good defender and i can seize opportunities when the opponent makes a mistake but i just can't seem to find the right tactics or provoke them without being simply blocked. Like i'm not creative enough ? No matter how many puzzles i make i don't even see improvement, actually i'm failing a lot more puzzles as time goes.
What brought you out of that zone ?
In general try to focus on not blundering obvious stuff like pieces or simple double threats. Once you think you have "mastered" that (everyone blunders from time to time, just try to avoid it most of the times, you get the point) then it is time to look for more complex tactics. Also, if you feel that the time of a 15 + 15 game is not enough, go for longer time controls. You can also play correspondance games to have more time to analyze. After each game spend some time to analyze it before moving on to the next one and try to avoid the mistakes you are doing.
Having a coach also helps with the last part, someone who can point to you what you did wrong is always a great aid :) (if you are interested send me a message)
Also, try to be more careful on finishing off the game, I looked at some of your games where you stalamated in an easily winning position (eg lichess.org/S5OVLcJv#125 and lichess.org/QDCNCM07/black).
In general I would say that you should be higher in rating, it's just some simple mistakes and maybe a lack of concentration towards the end.
Keep up the work though and continue to improve :)
A lot of things could "bring you through it." Probably the person that told you to do tactics was right. The guy that told you to review your games was probably right too. There are several ways to improve at anything: Practice, read, watch somebody better, get coached, or perform under pressure are a few learning methods that work with chess.
It sounds like you are heavy on the practice side. Try looking at better player's games or reading something like Chernev's book, "logical chess move by move."
I never thought this would be appropriate advice, but I would recommend learning some basic openings. Looking at your losses, most are from getting into positions that are difficult to play right from the beginning. For example, in lichess.org/v2NvETMq/black , you played 2... Nc6 rather than 2... exd4. In another game you played 2... d6, which is also quite weak. I'm not suggesting to memorize long lines, but you should make it a goal to make it past the first few moves without getting into a bad position.
I also suggest resigning less. As apostolis pointed out, stalemates do happen at the end, and even if you lose a minor piece in the opening, not all is lost. (Example: move 17 of the 2nd game that apostolis posted!) Don't expect your opponent to easily convert their extra piece into a win-- I'm 1800 USCF and still have trouble doing that!
Good luck. I see you are currently on a winning streak, and I hope you improve soon.
Try learning the importance of waiting moves / strategy. Strengthening your position doesn't always require an immediate tactic but the stronger your position is the more numerous and more likely you will be to find and pull off tactics. If it is a problem of foresight then try some studying that focuses on pattern recognition. Being able to look at a piece on a board and instantly see all it's moves, good or bad, is very helpful.
Example: I have this fat Polgar book called CHESS. Beautiful beast she is. It focuses on Mates in One, Two, and Three plus a section of combinations at the back. After studying it for awhile just by running through the Mates I found my Bullet rating going up by a couple hundred points easily. By making simpler tactics a part of my "muscle" memory I was able to focus on other parts of the game.
A chess coach would be able to help greatly.
To be good at chess is not an event.....it's a process. You are on track. Just top up with advices shared here.
My opinion is that you should focus on playing less and study more (basics, tactics, strategy, openings and endgame). Don´t focus only in one of those.
There are thousands of ways to learn (books, videos, personal coach). You should improve at all of it dedicating some time to each of them. Also, it´s a good advice to start playing at the higher play time and reduce it only when you achieve a higher level.
At your level, you should never resign. Not when a piece down, not when you think checkmate is just around the corner; you can learn a LOT from watching how your opponents convert advantages, even if they aren't the most clean conversions. (EDIT: You can also learn from watching failures to convert)
You'd be surprised how much this will help you; if you take even a few minutes to understand what each move does when your opponent is checkmating your king, you'll quickly pick up on some common patterns that you can either use yourself or learn to avoid.
Probably the most important tip; play against players that are significantly stronger than you. Expect to lose the vast majority of the games. You'll begin to notice tactics much faster, and you can learn a lot simply from seeing how they play.