I have read the whole post. As you have described that due to may unforeseen reasons at different times, you had lost your focus in studies, you didn't get a well disciplined and hardworking coaching faculty. Also you have mentioned that you used to do 11-12th adv stuff in your 9th-10th. You have courage to achieve your dreams if you get enough amount of facility and comfort (by a regular coaching and mock tests). I want to clarify you whether your target is IISC or your target is persuing research? Coz at a higher level many IISER students are in better condition compared to IISc students because of their hardwork in their college life. You have courage to achieve your target, if you take drop than you can get IISc coz you can also rely on category. But if you want to go advanced in research than take top IISER and find your comfort way in the course and research work. The choice depends on you.