What is wrong with me?!

Emily • Baby #1 on the way! Due 3/18
My husband (27) and I have been trying for a year!! And still nothing. I am only 20 years old. Girls my age are getting pregnant by accident and I can't even get pregnant on purpose. My husband already has a 7 year old girl. So I know it has to be me. Any advice? I take ovulation tests. Track everything. And trust me. We have been trying.