Why so certain that you'd botch your o'level math?
I think you just need to get a good tutor. Start
considering how you can work on your maths before you start
thinking of how to live the rest of your life. Its not all
hopeless.
I sucked at math in sec school (hardly passed), but did okay
with a B3 after getting a tutor to help me work on it. Oh,
and I was retained for a year also.
I sucked at math while I was at poly, but was determined to
finish 3-4 past year papers before each math paper. Since the
papers usually don't differ a lot, I was able to get As and Bs for
them.
And somehow, I got into uni. I suck at a lot of other
different subjects now, but I am avoiding maths like where I have
to.
Dude, don't let sec school math "determine" your entire life
ahead of you. Just tough it out and do your best to conquer
it.