To get that extension on your grad date, think about adding a minor that requires the med school prereqs. Like bio or chem or biochem etc.
I suggest taking at least one class in bioinformatics or healthcare administration/IT. This is a big scary area of flux in medicine and people who aren't intimidated by IT can have a leg up in med school interviews (certainly true for me). Also look into IHI and the checklist movement - that's classic sys mgmt.
Best of luck to you.
Looks like the following are cross minor options ...
MINOR IN MOLECULAR AND CELL BIOLOGY: BIOL-UA 11, 12, plus BIOL-UA 21, 22 and either At the Bench: Applied Molecular Biology (BIOL-UA 36) or At the Bench: Applied Cell Biology (BIOL-UA 37)
MINOR IN GENETICS: BIOL-UA 11, 12, plus BIOL-UA 21, Genetics (BIOL-UA 30), and At the Bench: Laboratory in Genetics (BIOL-UA 31)
MINOR IN GENOMICS AND BIOINFORMATICS: BIOL-UA 11, 12, plus BIOL-UA 21, At the Bench: Introduction to Genomics and Bioinformatics (BIOL-UA 38), and one of the following: Microbiology and Microbial Genomics (BIOL-UA 44), Bioinformatics and Genomes (BIOL-GA 1127), or Systems Biology (BIOL-GA 1128)
MINOR IN ENVIRONMENTAL BIOLOGY: BIOL-UA 11, 12 or the equivalent; one of the following laboratory courses: Field Laboratory in Ecology (BIOL-UA 16), Urban Ecology (BIOL-UA 18) or Ecological Analysis with Geographic Information System (BIOL-UA 64); and two of the following: Evolution (BIOL-UA 58), Introduction to Ecology (BIOL-UA 63), Biogeochemistry of Global Change (BIOL-UA 66) or Current Topics in Earth System Sciences (BIOL-UA 332).