Two things struck me, and of course they lead to two different issues and maybe approaches to college.
This, more than low test scores, stood out to me. If you attend a school that approaches learning differently, then schools like Penn may not been appropriate for you. The low test scores (aka, the traditional approach) seem to bolster that suspicion.
While I know students who have transitioned very well going from an unconventional high school environment to Penn, they also scored well with traditional testing (SAT, SAT subject tests). That doesn’t seem to be the case here.
Instead of asking “How do I make myself into a successful traditional student?” so you can go to named schools like Penn or UCLA, maybe you can ask “Where can I study that supports me and extends the same approach to learning to the college levelg” There are schools that may work better for you. Hampshire, to pick a college out of thin air, is test-blind. It won’t look at any standardized tests. Plus, Hampshire has a different approach to college education than other colleges.
This also caught my eye. Students often fall into the trap thinking it’s enough to understand the words of a new concept. It’s not. Practice is necessary to fully learn and internalize what the new concept means and does. This is especially the case in math, science but it also holds for English grammar and writing.
In order to do well on standardized tests, such as the ACT, practice is often necessary. If you spent your entire education in a traditional education setting with lots of standardized tests, you’re probably fairly well prepared. If, however, your school eschews standardized testing, you actually have to learn and practice how to take these exams.
So, depending on your particular situation, you can practice taking the ACT or look for alternative colleges or do both. If it were my child, I’d strongly recommend doing both.