My two cents is you are looking toward that upper-class stage of college where you have to start getting pretty serious about choosing your next step. A lot of people struggle with anxiety and doubt at that point, some make big changes (I did), and so on. But it is an inevitable product of the fact that college is going to end and something is going to come next.
OK, so do you want to go to medical school or be an engineer? To be very blunt, I think you need to have an answer to this question by the time you are a junior. Not that no one ever jumps off those tracks into something else, but both of those tracks are extremely hard ones, many more people start them and leave them than come to them later, and it is just going to make things way harder than necessary on you if you try to keep both of those options open during your junior and senior years.
OK, so if you want to go to medical school, I think the obvious answer is to stay at Carleton. We laid out the logic why above.
If you want to be an engineer, you could look at transferring, although that will be tricky. You could also, though, look at a 3-2 (or 4-2, 3-3, 4-3) program, or just a masters in engineering not part of such a program at all:
Carleton’s preferred partner for the formal dual-degree programs is WUSTL. WUSTL’s engineering school has a robust dual-degree program:
https://engineering.wustl.edu/academics/dual-degree-program/index.html
According to their FAQ, as long as you do their course requirements, achieve a 3.25 GPA (both generally and in math/science), and are endorsed by Carleton, you should be admitted. I finally note WUSTL is particularly strong in Biomedical Engineering.
However, if you look back at that Carleton page, they say a lot of people start off thinking about these dual degree programs, and then opt for a normal graduate engineering degree instead. And in fact, I note a lot of people will express skepticism about these programs, including because they take at least an extra year, possibly two.
But that is because really doing engineering right takes time and focus, and again it is tricky to transfer from a college without engineering and complete an engineering degree in four years anyway. So at this point, I am not sure a 4-year engineering degree is even a realistic possibility.
As a final thought, Carleton has excellent advising, including dedicated advisors for both pre-health tracks and pre-engineering:
So, these are the people who you should really be talking to. They will do the best job explaining your options, helping you evaluate pros and cons, and then executing on whatever you decide to do.
But again . . . I think even if they are not quite as blunt about it, they will probably in their own way make clear that you should likely be choosing between those tracks, not trying to stay on both.