Family planning

Hey, guys. I need advice. One of the only things I want in life is to be a mom. I have never wanted anything more. I’m so terrified that I won’t be able to get pregnant. I went to an OBGYN to be checked out and she said everything looks great but the only way to know for sure if I can get pregnant is to try. My SO and I have talked about trying for a baby in about a year. We have been together for over 3 years and we are both in our early 20s. So the other half of me wants to spend as much time with just the two of us for a little while longer because I know it’ll never be the same after having a baby. But the thought of not being able to have a baby upsets me every single day. It’s just the not knowing part that bothers me.