Did you try lukepros Algorithm for Beating Procrastination?

From your description I take it that the expectancy of the task is moderate (you reliably gain a degree), but its value is partly low: Personally you gain a degree but the thesis itself provides little value on which you could build and which might be intrinsically important for you.

The main problems seem to be delay as is often the case with thesis work. I'd think that your experience with pomodoros should help here: You could break down the thesis into parts, espl. the prose parts.

I'm not clear about your impulsiveness. It appears that you never had to work hard and were able to follow your interests. I can relate to that as it was the same for me. It is kind of a flaw of our society to make some things too easy (not that I'd cry about it). It can hurt us in the long run though. I got out easy: I found a motivation to work hard: Family, esp. my children.

You have to make your mind up on this. I'm not even entirely clear whther procrastination is a bad thing: It's our sobconscious way of telling us that the work has no or may not have long-term potential.