I would say start there, start in that uncertain space. Toni Morrison said that her novels always began with a question, so what is yours? What do you want to know? What are you trying to figure out?
Motherhood is more than just a phase of life or label to wear. I realized, once I became a mother, how much its this construct that affects everyone -- women and men, mothers and women who are not mothers, whether by choice, or circumstance.
You are whole and wonderful and beautiful just the way you are right now. You always have been, and you always will be. Oh, and also stop hating on your period so much!