If you believe in Multiverse theory, you may go back in time and change the past, but it's not going to help you whatsoever because you will also make different choices from that point onward. variables will come into play as to which you actually end up with an outcome that won't affect you at all.

Basically what I'm saying is that going back into the past and changing it only changes a different reality of your life. They reality you're living in at this point will not change at all. The only thing you can work towards right now is actually going to medical school now and not keep on waiting before the time finally passes and you regret not going at all.

I know I may be a little blunt here, but people are always trying to make excuses for what happened in the past. You can't keep holding onto the past mistakes. You should've learned from what happened and carried on to pursue your dreams of receiving your Doctorates and living a life of a full time Doctor.

I say right now to remember that past mistake and continue onward.