You are right - procrastination is due to fears and anxieties acting up and blocking our desire to work. A way to mitigate or get over that is to try and talk to that part of you, the part that's in fear, and ask it what exactly is it that it fears, how to make it feel better etc. It's actually the most common and useful way of self healing - talking to your emotional self (also called the "inner child").

Anyway, you seem very mature and it looks like you already grasped what you need to do when feeling afraid and anxious. Writing is a really hard process, and I don't think "powering through" it is good advice. At least not in the long term.