wanting kids. need help!!

I need help!! I'm 21 and I've been with my boyfriend for a while now. But just recently I've been wanting to have kids with him. And I'm not sure what to do I'm busy enough as it is with work and school but I still feel the want to have one. And my boyfriend already has a two year son and I'm not sure if he wants another one anytime soon. I'm not sure if I should tell him how I feel or just want for him to say he's ready for more kids. What should I do?