Hmm, how's that quote go? "What if I fall? Oh, but my darling, what if you fly?"
Sometimes the best things in life take a large risk to achieve. Sometimes taking that risk pays off, sometimes not, obviously. The question is, can you live with not taking that risk? When you're on your deathbed, would you regret not having made the leap?
It is a very big, scary decision, with a lot of implications. Do your best to make sure that you've considered every aspect of what it would mean to start HRT, and to not start HRT. And once you've covered all that, pay attention to how you feel regarding each potential decision. If, after all that, it's a thing you think you want to do then you're just going to have to take a leap of faith, but not before!
Personally what helped me feel better about my decision was all the little things I had done leading up to that point. Small, reversible bits of transitioning to sort of test the waters. Each one was pretty scary, I always thought "How am I ever going to look at myself as a man again after doing this, what if I NEED to be a man to be safe, or sane, and I'm completely destroying that self image by doing this". But I never regretted a single one of those small transitions, and in fact each one made me feel a little happier, a little more myself. That's how I knew I was making the right decision.
Sorry for the wordy post, and I know I'm headed in the opposite direction you are but I think it's generally applicable? Anyway, hope it helps