Off the top of my head, I'd say yes. Or at least cut down your commitment, while you figure out what you want to do.
Organizations and jobs (volunteer ones, too) change over time, and sometimes, we have no control over this. Nothing is worth the stress you describe. Volunteering is supposed to make you feel good. If this was a paid position, it sounds like you would be looking for another job.
Sit down and make a list of priorities. Write it out. If you want to ride more, than figure out how that can happen. I can tell you from experience that life is too short to worry about this stuff.
A few months ago, I commented here that organizations took advantage of volunteers, particularly women, to the point it made me feel like it was slave labor. Some didn't like that comment, but, basically, it comes down to the fact that I said before; volunteering should make you feel good. Perhaps my perspective is different, given that I have always worked in human service related fields. I don't feel the need to volunteer in "helping" things, because I do that every day in my real life paid career. I can see how this would be different if you had a business oriented career, where the bottom line was more important.
You have the opportunity to take the skills you learned at the co-op and build your bike! And maybe, you could even help others with their repairs, out of your home. One of the mechanics at a shop I used to go to left the LBS and now has a thriving business out of her garage.