Baby fever

I am 18, and my boyfriend is 20. We've been dating almost two years now, and are living together/ parenting a kitten together. 😊 I love him and I want to marry him, but he seriously wants a baby within the next couple years. I want a child, but definitely want to wait until I feel financially and emotionally stable. How do I break this to him gently? I love that he wants to be a father so bad, but I do not have the means to be a momma yet!