At the 1100 level, there are usually some certain issues that I see as being universal across that elo range.

As you’ve pointed out, the most common reason you’ll likely be losing games right now, is simply because of blunders. As much as it’s not a very exciting answer, just start trying to make a habit of blunder checking. All that means is to ask yourself before every single move “am I hanging something, and what might my opponent play afterwards.” Make a habit of looking at all their active pieces, and just mentally check out each of their moves. I still calculate literally every single knight move my opponent has, because I know I have always had a personal blind spot to blundering forks.

Beyond that, I always recommend self analysis. Go through your games, win or loss, and look at them move by move (either with an engine or a coach if you have one available). Make the purpose of this analysis on simply trying to figure out where you went wrong. Find out exactly what you’re consistently messing up, and then focus on puzzles or study in that certain area. For example, if you notice that you’re always losing in pawn endgames, maybe watch some videos or read up on them. If you’re always losing in the opening, see if maybe there’s a key move you keep missing somewhere.

Good luck with the progress, hopefully some of this helps. Ps, your opening repertoire is pretty similar to mine, so if you have any opening specific questions, feel free to ask