When are you ready?

I feel like idk if I'm ready ttc , my husband is happy and really wants a family, his ex had a kid and he basically raised him as his own for 5 years. I believe the kid was 1-2 yrs old when he started his previous relationship, anyway... since he is happy to start a family and we are not taking any precautions to prevent it, i wonder if I'm ready? I'm 21 yrs old, still in college, i work. And some days I really want to conceive, but some other days I feel like I'm happy for not being pregnant.. but at the same time I get upset every time I get my period.

Help!