I am wondering whether you might have jumped ahead in math. Math is an area where what you learn today is based on what you learned last year and the year before, and what you are going to be learning next year is based on what you are learning now. You want to make sure that you understand each step solidly before you go ahead to the next step. Jumping ahead in math usually does not come out well. Math is also an area where you need to understand the concepts. Definitely do not just try to apply formulae.
By the way I have a bachelor’s degree in mathematics from MIT that I earned a very long time ago. MIT is full of students who remember the one time that they got an A in math rather than their normal A+, or who remember the low A+ that they got rather than their normal high A+. These students still find MIT to be very challenging. MIT is a lot of work and the desire to work that hard needs to come from inside you, the student. MIT is not a good fit for every very strong student.
With a math degree from MIT my first full time job involved application of math and software to problems that needed computers to solve. In some cases we were using canned software programs to solve problems, and coming up with results that really did not look right. Someone (meaning the math guy, meaning me) had to figure out what was going wrong. I looked at what math the software was using and why it did not fit our problem. This was definitely an example where understanding the concepts was critical, and just understanding the formulae would not have helped at all (the programs were applying formulae correctly, they just weren’t using quite the right formulae for the problem that we were trying to solve).
Working 18 hours per week in a grocery store is a lot to do alongside high school and multiple AP classes plus filling out university applications and taking standardized tests. One of the key skills in life is to find things to NOT do. There are lots of things that we want to do. We each need to figure out what the priority is and focus our efforts. Working a job is by the way a good EC (as is robotics), and if you spend a lot of time working a job you might as one option think about reducing time spent on other ECs.
And yes, Massachusetts is a tough state for the national merit exam.
And @tsbna44 is entirely correct that there is no perfect school. There are plusses and minuses of every school. Finding a university that is a good fit for you is very important. Attending a highly ranked university is not.
When I see someone say “Top 20 or Ivy” I get nervous. One reason that I get nervous is that the top 20 universities and Ivy League schools are not all the same. They are not all going to be a good fit for any one particular strong student. You should be thinking about which schools would be a good fit for you. Also, if you are at some point interested in any graduate program, in general the students at the highest ranked graduate programs come from a huge range of undergraduate colleges and universities, and definitely not just from “top 20” nor even “top 50” schools. I have also found consistently throughout my career that graduates from highly ranked universities routinely work alongside graduates from a huge range of schools and in most cases no one cares where anyone got their degree(s).
And the other reason that “top 20 or Ivy” makes me nervous is that none of them are safeties for pretty nearly any student. You definitely also need to be finding safeties to apply to that you would be happy attending.
And only do ROTC if you want to serve in the military.
Best wishes.