Ethan,
I don't see how you can be ready for transition if you have not resolved this issue. If the start of transition risks your fertility, than it would seem you have made the decision not to have children of your own, since you are willing to risk this.
I have not started my physical transition either. I too am going to school and hope to eventually become gainfully employed again, so I can afford to transition. Right now I live on disability. I do have three genetic sons and one adopted daughter from a previous marriage of my exwife, who had this child when we met. I love all of them dearly, but there is a difference in the genetic children. They look like me, they have personality traits like me, they walk, talk and act like me in many ways. I do not love them any more, but there is a difference.
Had I transitioned earlier, I would not have them. It's a Catch-22. I would have been happier had I transitioned and not married, but I would not have my children, which also have been a source of great joy in my life. So, I guess I don't really have any good advice. Trust yourself.
Love always,
Elizabeth