I've been there. Do you want advice or just comisseration?
A place to express your frustration
Venting is a place where Lemmy users can rant/vent about anything that is on their mind. If you are annoyed or very pissed off about something, you can talk about it here and our community will listen.
I’m open to some advice
Try making a rule that you draw for 10 minutes every day, no matter what. It doesn't have to be related to your manga, but it can be. You don't need to be good, you don't need to be working toward a grand vision, you just need to be doing something.
I started doing this with painting. Just 10 minutes before bed. If I have to commit to a longer time, I'll never do it. In 3 weeks i turned out a painting i feel good about. Right now I'm participating in Inktober; there's a new prompt for an ink sketch every day, still I spend 10 minutes. I haven't drawn with ink (or anything really) in a decade and some of my pictures look decent and some are terrible, but I'm making them. And making things inspired me to make more things.
If you're stuck on a project, you can try these oblique strategies designed by musician Brian Eno.
Join us at c/artshare and post your work. I'd love to see it.
My projects don't get very far before they turn into "open editor, stare, do something else"