I think largely your answer is going to, unfortunately, have to be introspective. It is not really possible to determine your future potential based upon the highly variable quality of education, test structure, and mere factors of happenstance.
That said, from my experience in university, many who are now relatively good mathematics majors did both well and poorly in secondary school. You must ask yourself whether indeed you really are interested in mathematics, if so then why, and then analyse your own particular character as honestly as possible asking yourself if you have the needed temperament. Many who fail do so not merely because of their lack of competency, though this does happen, but because they do not have the patience for academic studies. If you do this and conclude you still want to continue, though you may still reasonably have perfectly understandable doubts and concerns, you should go for it.
Depending on the type of mathematics one studies, and their own particular strengths, it can be hard or not. Often, many do well with the higher degree of abstract generalisation of pure where some may find difficulty in, some others still in the more concrete numerical methods of applied mathematics. Thus, consider what kind of mathematics interests you and whether you are confident in your abilities to learn it.
One caveat, since you did not mention why you wanted to
study mathematics, except maybe interest, also consider what is the essence of what it is you want to study. Many who start of in physics, for example, later switch to philosophy because what interested them was more philosophical in nature than scientific.
Having said all this, do consider this advice as vital which is probably the best advice I think anyone can really give to an aspiring student: study, study like mad. Not merely for your exams, but out of interest as well. The worst that can happen is that you fail, but you will be a more knowledgeable and therefore better person for it.