How do you deal with baby fever?

(Discussion of infertility below) I'm a 20 year old female & I've wanted to have children my entire life, but over the past, say 8 months or so, the desire has gotten such that it feels like an absolute need. I'm depressed over the fact that I cannot fulfill this dream yet, and it will still be another few years before my bf and I can. I know I'm young and there's no rush, but I'm also terrified because infertility and other reproductive issues are very very common in my family. To be frank I feel like it's my purpose in life to be a mother so, I feel utterly useless. It's really affecting my everyday, so I'd like to find ways to express and calm these emotions. Unfortunately helping care for other people's babies isn't currently an option. :(

Tl;dr- I have horrible "baby fever" and need advice on how to cope with it until I can have a child.