As I've said previously, the struggle is real. This especially is something I can very much relate to:
I start with high hopes only to slowly lose interest or motivation after a few posts.
I think, though, that when you talk about how you keep coming back to writing, that's what other people mean when they say they "can't not write." Even if it's difficult, it's still a compulsion of some sort. I think the important question is to figure out what's getting in your way.