Science majors-- like engineering majors–have some pretty strict course sequencing. There are pre-reqs and co-reqs you need to complete before you can enroll in upper level courses. Additionally, depending upon the size of your college, not all electives are offered every semester. Or even every year.
I recommend that you get a copy of the the course catalog for your college and use the school’s registrar’s site to see if you can fit in all your major courses & med school pre-reqs into 3 years.
If you decide you want to finish, and are able to finish in 3 years–then it’s your call.
BTW, what’s your Plan B?
A Plan B is an alternate career that you would be happy to pursue just in case med school doesn’t happen for you. This is not a dig at you. Every pre-med needs a Plan B because only 40% of those who apply to med school get accepted. (And 75% of freshman pre-meds never even get to the place where they are applying to med school.)
Maybe you could use some of the space freed up by your DE credits to add a second major to bolster your post-college employability. Just in case. Biological sciences majors have very poor employment prospects. And not just at the BA/BS level. Even at the PhD level bio majors face pretty bleak employment prospects.
FWIW, both my Ds had a Plan B career in mind during undergrad (medical physics for one; biostatistics and healthcare policy for the other) . And both had a second major in mathematics that offered a huge boost in their post-college employability and dovetailed nicely with the Plan B careers.