hi You_Zhi
ive been through a similar situation as well.
I did not even pass the compass test back in JC days.
But I tried again after Uni and was declared to be suitable to be a pilot on my 2nd try.
I guess if you really want to enter SIA, you should try to obtain a degree first?
After that, you can try the compass test again (I'm sure u can improve in future).
You can even try SIA directly after Uni as you are still 5-6yrs off the requirements now.
No worries and Gdluck!