What is expected of you as a part-time librarian vs. full-time?

I have been at my position for a year now. I’m a part-time librarian at a small branch in our system. I work every Saturday. My co-librarian works FT, she never works Saturdays so I am in charge of all of the big library events. In my previous position, part-time librarians were a little more like extra help. Yes, we worked the reference desk and did programs, but nowhere near the program load I am expected to do as a part-timer. I know the job market is not good right now, so I’m hesitant to jump ship, but this position is also souring me so much on the field that it makes me want to leave the work all together. I have talked to my boss and he’s not helpful.

Advice is welcome, but I really just want to hear what the workload is like for other part-time employees vs their full-time counterparts.