You are allowed to not want to be around a penis, but I do encourage you (for your own awareness and benefit, not to change your mind at all) to look up the many differences in penises attached to people undergoing estrogen treatment. One of the differences has to do with the ability to become erect or not, and the entire vibe going on down there.

I would also say, your preference is entirely valid, but that sounds like a level of panic which could be lessened by some talk therapy. Your anxiety and the choices you make as a result aren't wrong, but I feel for you and I hope so much that you have ways to manage the likely reasons for that severe anxious aversion. <3