While going through your post, I began to believe it's my life story except the business part.
85% in 10th, 52% in 12th and 67% in Btech which took five years due to 11 backlogs in 5th semester. Total 26 marks in IITJEE - 2014 after preparing from IITians PACE.
I'm currently employed in Australia's no.1 Bank as a Data Analyst and have always worked in reputed MNCs. No paid courses after degree too.
What I can suggest is, believe in yourself, don't think and try to do everything. It's okay to start something small even if it's a business or a job. Just do something and keep getting better at it. The tortoise actually wins the race EVERY F*CKING TIME.