chem e undergrad: did I just sign up for another death sentence?

mrund3rd09

I'm a third year planning to graduate 1 semester early. Last fall, I took 18.5 credit hours and worked 2 jobs (paper delivery and research assistant). I was pretty wasted by the end of the semester. Subsequently, I got depressed the following spring semester and had to drop down to a part time student. I don't know if it had anything to do with the work I put myself through the semester before.

This fall, I'm taking 15.0 credit hours and working 3 jobs (paper delivery and 2 research positions). It's too late for me to drop any classes, but I can take one of my classes p/f if I choose to. I might do just that because the professor I have for that class has the tendency to suck the happiness out of people.

anyways, I want to be able to focus on research, meanwhile contemplating the possibility of going to grad school. I would like to prioritize research over my classes, but I don't think that's possible. At the same time, I pretty much have 1 year to demonstrate my abilities as a researcher before it's time for grad school applications. Can I get some suggestions?