You're making progress, keep it going.

We all have frustrations, and I've never seen perfect instructions. You already found that youtube can be helpful, and the best advice there is says to test-fit or dry-fit many times before getting the cement.

But when you feel the frustration rising, put the kit and the tools down, go for a walk, watch a movie, something. In my case, if I keep pushing when filling up with anxiety and anger, I end up making a small problem bigger.