I've been feeling comfortable uploading 5 pages per week(more if I have more time), always on weekends. I've started 2 months ago, and the readers I have seem to be comfortable with that. Every month I completed a full chapter (with 30 pages or so each).
What I do to stay in the fresh zone is updating a spin off story drawn in a much simpler style that I can update daily, 1 or 2 pages per day. That also gives your subscribers something to read about and keep you in their mind
Aside from that, I have another series in which I upload the art of the main comics and extras of it, giving you readers some extra material is a good idea too. (In the case of this one I don't have a schedule at all tho. Still I try to upload something at least once a week).
And as they said above, consistency is really important!
I'm also a student, and I'm working too, so I get that this kind of things take a lot of time away from doing the comic, as @zetina said, find something that works for you ;D
Best of lucks finding more readers! And don't get desperate if the subs don't go up fast, that's pretty normal. The only people I've seen get subs in just a few days are the ones who already have a base of readers outside Tapastic of if they are featured in the "staff picks".