you have to remember some of the people who got interviews change their minds or was only using BOH as a back up, last year someone rejected a BOH offer as she got a pharmacy offer in the 2nd round UAC and in another year someone did BLibStudies instead.
If I had it over again I'd just do the normal BSc. Probably would have done chem, phys and bio in first year then major in pharmacology and immunobiology but thats just me.
If you end up doing med sci, you can always try to find work as a dental assistant. That way you will get some idea of what its like to work in a dental environment.
I'm aware a lot of people do very well in gamsat without a science degree, its just science students that have done chem, phys and bio at uni dont have to do as much prep for it. Also, a lot ex med sci students dont have to do as much work as other students in the first year or two of med or dent as they already all the science stuff inside out.
good luck with whatever you end up doing.