DO schools are decidedly less competitive than MD schools; if you have a 3.0ish and good MCATs (28+) plus extracurriculars and some health volunteering (or EMS or something) you'll be extremely competitive for DO schools--and even some MD programs.
Don't give up. Keep plugging along in the premed classes. Go get extra help (don't be afraid to approach professors and be honest about what you are/are not comprehending). Sometimes TAs are VERY helpful--and less intimidating--than science profs in this regard.
Above all, you need to be able to keep your personal life and your academic life (i.e., the stuff that will get you into med school--classes, volunteering, clubs, etc)--SEPARATE. If stuff is going down in your personal life that makes you lose focus, you should get help to solve the problems, or at the very least learn to compartmentalize your life so that the academics don't suffer too much. Yes, you have an opportunity to give excuses at the interviews for med school, but they should really be good ones (true family issues) and not Dawson's Creek ones (my girlfriend/boyfriend is really clingy this semester).
I wound up being pretty scattered in college (family issues and Dawson's Creek ones), and finished with a 3.2 overall and 3.1 science, minimal extracurriculars and no volunteering (decent MCATs though). I wound up having to take a few years off and do grad work before I really felt that I was competitive enough to get interviews at MD schools.
College is your time to shine--to overcome all the stuff that happens to be present in your life/personality/situation that you feel is holding you back. Get out there and have fun, but diversify your experiences and focus on what's important.
Start a club, take an EMT class, join a publication and write some college articles about the food in the cafeteria or some liberal cause halfway across the world. They like that stuff. Whatever you do, do what you like, so when they ask you to speak about it, you can speak with a little genuine passion and excitement.
Just my .02.
Best of luck to you.