First of all, relax. You are doing well.
A perfect score on the SAT is impressive. I was a math major at MIT, so I did know lots of students who got perfect scores on the math part of the regular SAT exam. However, I do not know if I have ever even met anyone who got a perfect score on the overall SAT or on the English part of the SAT.
Your successful business is similarly impressive. One thing to think about: What part of this process do you enjoy the most?
MOST students change their major after they start university. This is very common. Personally, as a math major, at the point where I graduated from university I still had no idea what I wanted to do with my career or my life. I figured it out over time, with the help of a few jobs in various fields. Most people who end up successful try a bit of this and a bit of that before they figure out what they want to do.
Quite a few high school students know what they want to do. Then six months later they have changed their mind and want to do something else. Then they get to university and take a few classes and change their mind again. Then years later they find that it all worked out just fine in spite of the fact that they changed their mind a few times.
Your freshman year of high school will be much less important compared to your sophomore and junior years. Some universities do not even consider your grades from your freshman year (the various Universities of California and as far as I know all universities in Canada come to mind as some examples). Even at universities that do consider your freshman year grades, improvement over time in grades and/or improvement over time in the rigor of the courses that you take will help your university admissions quite a bit.
I think that you might want to read the “applying sideways” blog on the MIT admissions web site. The point of the blog, as I understand it, is that you should do what is right for you, and do it well. If you belong at MIT this is likely to help you get into MIT. If you belong somewhere else (the vast majority of strong students belong somewhere else) then doing what is right for you will still help you get accepted into a university that is a good fit for you.
You should also keep in mind that there are hundreds of very good universities and colleges in the US. You do not need to attend MIT or Harvard to do well in life. You also do not need to get a bachelor’s degree from a highly ranked or famous university to get accepted to a strong graduate program. If you look at the various students enrolled in highly ranked graduate programs, you will find that they got their bachelor’s degree at a very wide range of universities. Finding a university that is a good fit for you and that you can afford is important. Attending a big name school for your bachelor’s degree is not.
Students do very well with degrees in a wide range of fields. I have mostly worked in high tech, so I mostly know people who majored in computer science, engineering, or mathematics. However, I know successful people with degrees in multiple other fields.
By the way, I do have a daughter who works in biotech, and who has done cancer research. An MIT researcher once defined research as “you might fail”. Research takes a lot of patience. Thomas Edison when he was working to try to invent the light bulb said that he hadn’t failed some large number of times, he had just successfully identified a lot of approaches that do not work. Cancer researchers similarly spend most of their time successfully identifying approaches that do not work. Biotech research can be a good career for some people. It might be the right career for a daughter. It would never have been the right career for me. We each contribute to the world in different ways.
My biotech daughter started university as a languages major. She switched her major after one year. Having a year with a different major did not stop her from doing well in biotech.
As a math major, I knew several students who were also math majors who changed their career path after getting their bachelor’s degrees. One went into acoustics. The last that I heard he was working to make European cars quieter. Another went to law school. Lots of people change their main focus at several points in their careers.
For now, get some sleep. Relax. You are doing well. Over the next few years (including four years of university) you will be exposed to a lot of options. You will figure out over time what is the right option for you.
No, it is not too late. Are you on-track to get as far as pre-calculus while still in high school? Will you have two science classes by the time that you graduate high school? If so then you are on track. Jumping ahead is not needed to do well in STEM fields.
Being fascinated by everything that you learn sounds like someone who could do well in a STEM field.
Again this sounds like someone who could do well in a STEM field, if that is what you decide that you want to do.
You are still young. If there is some student somewhere who is one year ahead of you in math, that does not matter. You have plenty of time to catch up. Life is not a sprint. Life is a marathon.
I know multiple people who have been very successful. As far as I know, none of them took the shortest path to get from wherever they started to being successful. They tried a bit of this and a bit of that, and eventually figured it out. You will figure it out also.