I am stuck at 1300...

You perform actually very good. In a few months you rised to 1300. At that level, opponents are stronger than U1100. At this point you need to study. More Tactics excercises and the book Simple Chess by Stean will help you improve.

I think your problem is that you're not really thinking deeply about any positions. You're just glancing at the board and making a move without actually calculating it out.

Take a look at this blitz game you lost. It was a 10 minute game, so you had plenty of time to think.

You spent 7 seconds thinking, then blundered and played Bg4??

After your opponent captures the pawn, you spent 8 seconds thinking and blundered again and played Bxe5??

You completely ignored your opponent's threat, and you got punished for it.

I believe that if you just stopped for a moment, considered your opponent's defensive resources and did some relatively simple calculations, you wouldn't have blundered a piece in the opening like this:

They say when it comes to tactics, you should examine all checks, captures and threats (particularly big threats, like mate in 1 threats).

But you also need to examine tactics that your opponent has against you. Consider all ways in which your opponent can put you in check, capture anything of yours, or make a mate in 1 threat against you.

Doing this after every move will prevent most of these blunders.

Another thing is being aware of "undefended pieces", as these are often victims of tactical blows.

When you have an undefended bishop on g4, and another undefended bishop on e5, that should raise alarm bells. Is there any way your opponent can punish you for having 2 undefended pieces?

I invite you to watch my videos:
https://www.youtube.com/watch?v=M1kptm4dwrg

Learn from your games

Same here.

https://chessmood.com/blog/golden-method-to-increase-rating-in-chess This article will be very useful, Also find a lot of good and helpful articles in ChessMood blog.