Everybody blunders, but better players blunder less. Don't these blunders discourage you.
These are things that will help you reduce blunders
1. Solve easy and harder tactics problems.
- You solve easy problems for pattern recognition. You solve harder puzzles for calculation improvement.
2. Always study your opponent's last move.
3. Always look at the whole board to see piece positioning
4. Before you make a move, check if there is a tactical drawback.
5. Stop playing bullet chess.
There are situations where you are winning easily and it makes you pay less attention to your opponent's move. This could result in a blunder. It is important to always study your opponents last move until the end(even if you are winning).
Every game I play, I reach a winning position albeit with a few inaccuracies from both sides, but regardless, I always end up blundering so all the good moves and my position don't even matter. Every chess game is literally the lottery even against people that are much worse than I am... I feel like it doesn't even matter that I am improving my game knowledge because of these dumb blunders. I feel like quitting chess just because it is so frustrating.