The way I made the decision was to remember how I felt as a male and that decided it. There was no way I ever wanted to go back to that. In your case, I suspect you may also have to look at your recent life and see if there is anything there that's worth holding on to. Doubt is common and nobody gets on the table 100% sure they are making the right decision. I know the first time I was 100% sure of my decision was as I was waking up from surgery. I hurt, I was blind and I wanted to go back to sleep but I knew it was the right decision.