Hello Aspirant.

As you've mentioned that you've got 91.38 percentile in JEE main examination and assuming you're from general category then according to the formula

Rank=(100-percentile)*8690.10

Your rank is around 74,820-74,850. At this much rank you won't get Computer Science in any government institution but you can get private college at this rank but there might be an issue where you'll need to compromise with your branch. Try giving more paper such as BITSAT UPTU, VITEEE.

No you won't get bit mesra untill you have some certified quota.

Best of luck !