This will give you an understanding of which topics make sense to you and which you can barely follow. From that, you will need to catch up but where from depends only on your level. I guess, you might have some Khan Academying to do to catch up with the school program.
After you are done with The Foundations of Mathematics, I think you can take Andrew Ng's courses and go from there. I also use https://www.routledge.com/A-Concise-Handbook-of-Mathematics-... as a general reference when I need to look up a topic a have a rather vague recollection of.
This will give you an understanding of which topics make sense to you and which you can barely follow. From that, you will need to catch up but where from depends only on your level. I guess, you might have some Khan Academying to do to catch up with the school program.
After you are done with The Foundations of Mathematics, I think you can take Andrew Ng's courses and go from there. I also use https://www.routledge.com/A-Concise-Handbook-of-Mathematics-... as a general reference when I need to look up a topic a have a rather vague recollection of.