Hello everybody!

I just got admitted into arts stream in a jc and i opted for the following subjects: h2 econs, h2 elit, h2 geog and h1 math. Actually, i have always wanted to get into sci stream and pursue medicine/biosciences in uni. However, the funny thing is that i am rather weak at science and math and i do not score well in them! I do much better in humanities and language subjects instead.. As seen from my o lvl results:
Eng- b3
Chi- a1
Hchi- a2
Emath- a2
Amath- b3
Bio- b3
Phy- b3
Chem- b3
geog + ss- a1

My worries about my chosen jc subject combi are that 1) my choices in uni is very limited and no matter what i have to get straight As to pursue Law or Business(which i am unconfident of) 2) i have no elit background 3) i am giving up my dream of studying medicine.
If i really want to go to sci course, i have to appeal from arts to sci course.. Is it worth it? At the same time i am also apprehensive that i would not score well in sci stream and regret my choice..
Really in a dilemma and time is running out!!
Seriously do appreciate your views and sorry for the long post