It sounds like you have had some experience up front of what premed classes are likely to be like. This might help you in the long run and might mean that you are well prepared (at least emotionally). I expect that many premed students do similarly get at least some hint in advance of how hard classes might be.
And if you find the first two or three premed classes to be relatively easy, do not expect that they will all be that way.
And if you get a few B’s, do not freak out. Plenty of students get accepted to medical school with some B’s (and maybe even with a C or two).
A premed student can major in almost anything. Some people major in public health and end up in some sort of medical administrative roles (although the person I know best who took this route has a degree in nursing and a masters in public health). Given that you will be taking premed classes, it seems likely that you will be starting off with strong science / biology / chemistry classes, which suggests that if you want to do it you could pivot to a scientific research role. It is very common for students to change their major in university. Sometimes this is a large shift, and sometimes it is a more subtle shift between at least somewhat related fields.
I have heard that students graduating with a bachelor’s degree in biology have limited job options, and the jobs do not pay very well. Something similar might be true in public health. However, my younger daughter with a bachelor’s degree in biology had pretty much the opposite experience. I think the main issue was that while her biology-major friends were in a hospital getting premed experience, my daughter was in a lab doing research. She got familiar with a number of lab techniques that were useful to biomedical researchers. Then after graduation she got a research job pretty quickly. What experience you have while you are in university can make a significant difference one way or another even among multiple students with the same major.
It sounds like you are in a very competitive high school. Try not to let the other students get to you. Once you get to university pretty much wherever you go there will be lot of students who are happy to be there, and probably a few who wish they were at Harvard instead (unless you are at Harvard, in which case there might still be a few students who wish they were somewhere else).
From what I have heard I think that it would be a good choice if you get in, and I think that your chances are reasonable. It is just very hard to predict.
And yes your safety or safeties are very important. I will take your word for it that you have this covered.
Best wishes.