I'm confused, I can't decide. Please help!

I'm a BSc CBZ student, rn in 2nd year, 3rd sem. I had taken 2 drops for NEET preparation before joining BSc. I aspire to become a theoretical physicist. Only TIFR allows non physics students into integrated PhD physics. Is this realistic or only on paper? Can we actually self study to be capable enough to get selected?

My question: should I continue with BSc CBZ and self study physics and math, or should I join BSc PCM from 1st year rn?

Joining BSc PCM will waste another year.

Whether I continue or restart, I have to rely on self study, as I can't rely much on my college. If I have to restart, I should do it only for the sake of degree certificate.

Please help...