Awww, I read your comic, and to be honest, I think you might have to go on a hiatus. Make sure to announce it, though. You do seem to be stuck between a rock and a hard place, and I honestly don't know what to say. From what I can gather though, the people on Tapas are really nice, and will understand about school and the like.
A quick tip for motivation, draw your comic bit by bit. For me, if I'm not motivated it can take me over a week to draw for panels, but what I do is force myself to make a messy sketch, then build it up as you can. A line here, fill in this eye, it all adds up. I might ink in a frame while taking a break from something else, but if you really need to, stop. Step back from the comic and forget about it for a few weeks, it really can help.
I hope I was able to help, and that things will work out soon enough! If you ever need a chat or just to rant, feel free to private message me, ok?