Should I work or take out a student loan?

I'm currently a junior in college and want to have a career in healthcare in the future. I plan on applying to the medical, p.a., and pharmacy schools in my area when I get my B.S. in Biology. The problem is that my overall g.p.a (3.0) and science g.p.a. (2.5) are considered terrible to admission boards and I have no significant extracurriculars, volunteering or shadowing hours to make up for my g.p.a b/c I always work part-time during the school yr. and full-time during the summer. Being unemployed isn't an option for me because the Stafford loans I currently get don't cover all my expenses (bills, rent, food). Also, my parents can't help me because they both have extremely low incomes. Basically, my question is should I continue working and hope that the admission boards will take my financial situation into consideration or should I take out a private loan to cover my last 2 years as an undergrad and stop working in order to be able to participate in volunteering, shadowing, etc