I wish I could be in two places at a time...

I'm a college student and a member of three student organizations (it used to be more than that, around seven, but it was kind of overwhelming, so I decided to resign from most of them). In two of the organizations, I'm in a middle-leader position (like the position right under the president or something like that), so I'm expected to handle my departments. Meanwhile, right now, since I'm a senior, my study requires me to spend most of my times for study-related activities, which means my time for the organizations is reduced.

My problem is my inability to communicate about all of this with either the president, the vice president, or even my partner in the department. I just can't say that I'm busy with my study, because I think they would say something like, "We also have studies to deal with." Besides, I kind of don't want to show them that I'm facing a problem. I don't think they're close enough to me to know this side of me.

Now everyone in the organizations keep demanding my presence, but with all the discussions, group projects, and assignments, I don't know if I can handle this. Resigning had ever been in my mind, but then I don't want to disappoint my partner, and generally everyone who seems to rely on me.