I finally did this by letting go of my perfectionism but I don't want to let go of improvement.

I tend to have similar issues, where trying to perfect things lead to a complete arrest of progress. The advice I want to give myself is to always try to improve, to but improve on what I wrote 4 months ago, not 4 minutes ago. If I focus on analyzing and improving stuff that I'm not actively writing today, hopefully that allows what I write today to not become an obstacle to writing more today.