Dear Humera,
First of all marks and percentage of 12th class are not relevant for pursuing CA. I had seen an average student doing CA as well as completing CA. A math, bio students and an engineer doing CA as well as completing it. Its all your passion and dream to become CA.
CA is all about patience and lots of hard work.
Take an independent decision, do listen to what others say but its you who should have interest and dedication towards it and definitely you will be successful.
HOPE THIS WOULD HELP YOU!!!!