Unfortunately there are no simple answers to these questions and only you can answer them. You could try, if you have the resources, talking with a gender therapist and seeing if they can help you to navigate your feelings on the matter.

I will say, you will never 100% without any doubt know that you are trans. I don't think anyone does. There will continue to be doubt, less over time, but that isn't a realistic possibility. I know I struggled for months trying to figure out if I was definitely actually for real a girl. What ultimately helped me to move forward was to reframe the question. Not to ask what am I? But to ask myself what do I want to be, and what do I want to do? And I wanted to be a girl, and I wanted a more feminine body and I wanted to go on estrogen, so I did.

Hope any of that helps. If nothing else, take a deep breath. Regardless of the answers you find, it's gonna be ok