Endometriosis

I am 21 years old and lost. I have wanted to be a mother since I could understand the process. But since I started having periods they have been unexplainably painful. With no answer from the doctors. I made an appointment to go to the OBGYN and I am terrified that they are going to tell me I have endometriosis. My mother had it, and every symptom she's said, I have. I know I'm probably worrying over nothing but I haven't had any children yet. I didn't want to until I was older. Now it might be too late... Thanks for letting me vent ladies.