I still read all the time, about traders and their biggest mistakes and they actually mention that many don't hold long enough, however, it sounds like you are holding on too long and the price drops on you.

Just the act of typing/confessing your sins on here is already acknowledgment of you knowing what you need to do differently. I know I have gotten better as I don't fret nearly as much when I get out and see that the price still went up a bit, sometimes a lot, but I move on and look for and wait for the next trade.

You'll get better.