You are so young. Don’t do all this to yourself.
I absolutely am sure that the reason you’re doing this is that you’re already concerned with college- that’s why you’re here. I have news, though- students who just take 4 math credits also get into prestigious colleges.
If you’re STEM-oriented, join a STEM club! Math club! Robotics! Anything! You don’t need to overload yourself like this. Take a summer class if you really want to in your junior year or something.
I can promise you one thing, though: You have no idea what HS is like. That isn’t meant to be rude or mean- you just don’t know yet. It’s a lot, and you sound like a student that will have a lot on your plate. I’m rooting for you, but don’t rush before you’re even in the building. Focus on building a strong resume outside of just the classes you’re taking.