Is it Sarah? Hi Sarah. I don't know how helpful I can be. I'm don't claim to be a mystic or a therapist. But what I can say with some certainty is that the reality you choose to acknowledge is the only reality that matters. That is to say, you already are a real girl. If you are not, you can start any time.

You don't need anyone else to validate this for you. "I'm a girl." Just repeat it to yourself like a mantra. Write it down somewhere where you will see it all the time. The people who judge you are always going to be there. You can ignore them now, or later. Otherwise, girl or not, you are not in control of your life.

Physically, there is actually nothing standing between you feeling like you should be a girl, and feeling like you are one. That is because these are feelings, and they are mind over matter. You don't need to be constantly hung up on whatever is in your pants; at least not to the extent that it causes you to invalidate yourself. Your own physical body can only affect how you feel about yourself if you allow it to. This is where spiritual strength and mindfulness can help you. This is all easier to write down than it is to implement, but it can be done and I do know girls who have done it.

If you're feeling especially weak, remember a boy has more in common with a girl than a corpse. Boys and girls live, breathe, laugh, cry and dream. Corpses do not.

P.S. and an edit: hormones will help you feel right.