I am wondering if it would be worth emailing departments that I haven't applied to this year, asking if they'd be willing to take a look at my application material. Any advice, or should I just wait till next year?
I applied to too few places this year, because I couldn't afford all the application fees. I'm saving up now but I feel bad that I don't have anything planned for next year, and I really want to begin my higher education since I feel strongly about it.
The short answer is yes it is too late. The long answer is that usually only top programs have only one round of admission and other schools actually have also a spring round of admissions so you could trying going for that. This is not common but I found a few schools that do that, and some of them are actually decent schools. But I would say 85% don't accept late applications.
How about getting a lab tech position at your current school and get more experience/pubs under your belt?