Don’t get discouraged. I looked at a recent game you lost. You were playing way solid and leading most of the time. The game turned when you made a simple mistake to ignore your opponent’s insignificant capture of your stone. If you tenuki’d to kill the important ones of your opponent instead, you would’ve enlarged your lead. Really a common mistake at your rank not to look beyond opponent’s current move, not a big deal at all. After that, you tried to escape unimportant stones of yours. If your opponent played very fast to capture those stones, it might not be he/she had read the whole thing out. It’s really only moves if he/she had made up the mind. It’s good tactic if mind is already made to play fast. It projects confidence to the opponent.
Then again, it’s quite often we get beaten by “weaker” opponents. We all suffer from that and hate it, but it is part of the game.
Keep playing and enjoy the game.