PS: I didn't understand this: " I reviewed my mistakes up to the openings only."
This means stopping game analysis until the point where you find your first mistake and maybe checking a few more moves if this corresponds to the opening phase. The idea of analyzing your games up to the point where your first mistake arrives is to learn from your mistakes and expand your knowledge.
You don't necessarily have to stop at the first mistake or inaccuracy, collecting a little more isn't bad, but the idea is not to analyze the game too much because what you want is to extract the knowledge corresponding to the opening ideas.
This is recommended if you play many fast or blitz games online, but I do not recommend this with slow games, especially if they are from a tournament you have played, in these cases it is good to analyze the complete game.
Thank you this makes me want to get really good at chess