Happy for you that you’ve turned it around for school! That’s fantastic! I bet it feels great.
I still think that it’s probably a better idea for you to plan for moving on to college next year, rather than a post-grad year. The reason that I say this is that you’re of an age to go to college next year, and I have a feeling that you would be happier with the independent environment of college, rather than doing a PG year of high school.
Assuming money’s no object, you should take a look at this thread from last year, regarding applying for college with a less than stellar high school record. S21--not an easy path, happy to get some input at this stage - #36 by Cheeringsection. But I think that your best opportunity to wind up going to school with students of similar ability is to start at a public college in your state, Maryland, from which you could transfer to U Md. There will be plenty of kids as bright as you at U Md. Do extremely well there, and there’s no reason that you wouldn’t be able to get into a prestigious MBA program, if that’s what you want.
I don’t know if a fantastic senior year, plus a fantastic PG year, plus a stellar SAT would get you into, say, Fordham, rather than a school that accepts 75% or more of applicants this year. Better to start college next year at a school you can get into, and then transfer if you do extremely well and still want to transfer.