Gala - that sounds like an EXCELLENT background for medical school here. Don’t fall into the trap of talking yourself out of it upfront! Having a finished degree is not so crucial as you think. Although they don’t accept foreign degrees, that doesn’t mean they don’t recognize that you have completed them. Looks like you have the rest of physics, Bio and Organic Chem to take. The A’s so far are GREAT! So are the volunteering hours …I would keep that up.
You don’t need a formal post-bacc. If it is possible for you to take your remaining courses at a 4-year college that WOULD help make you more competitive. Having one or more letters of recommendation from the faculty (at least one from a science professor) is important. Sit down front, ask questions 
A 4-year college will also have premed advisors. However at some schools these are less helpful than at others. One strategy folks have used is enrolling as a transfer degree-seeking student. Get the usual “junior year” medical school advising and assistance in applying. Then apply. You need not finish your degree. If, however, you want to take some upper level bio courses, or biochemistry during the year after applying (the “glide year”) that could be valuable to you - not a necessity.
I think you are well placed thus far to be a competitive candidate, as long as you complete the 90 hours (a common requirement)
Kate