Hello! I'm two years your senior- and I'm trying to decide between a medical field career or mathematical biology.
Mathematical biology is pretty interesting; and as a more spatial sort of mind, I think I'd prefer the modeling side of it.
It essentially uses principles in mathematics in order to explain or better demonstrate biological phenomena. The Hardy-Weinberg equation for the diversity of alleles in a gene pool given the expressed phenotypes is an example. (Actually, something to note; it's called the Hardy-Weinberg equation because it was the product of an English mathematician and a German physician, Godfrey Hardy and William Weinberg, respectively.)
That's more theoretical, though. If you were more of the creative sort, you could use programming and mathematical equations to plot data from studies, like a biostatistician with pretty pictures.
If you have questions, just PM me.