I can't tell if you are pessimistic or realistic. Both can be true.

But if you failed again, why try to do this on your own? There must be ways to study this type of math with a tutor/school, even though you are supposed to have been finished with school.

I tried to teach myself math for years. I study physics now and do fine. But I completely lacked the confidence, on my own, to study it, keep studying it, sign up for an entrance exam, and pass it.

And I now are a person that ought to have a knack for math. And it was hard for me, doing it solo. If you can't do it solo, get assistance.