Advice

Ok, so my bf and I have been together for 3 years. We were both in pretty bad relationships before we found each other. He has a 10 year old daughter that he has full custody of. And I have full custody of my son. We have discussed having a baby together and he told me yes. So since then, I have been hinting around that I`m ready. I have had baby fever for about a year now. But every time I try to discuss a time frame, he always says that we have to figure out space, sitter, expenses, etc. And he acts like he doesn't want another baby. So I get pretty down about it. He's sending me mixed signals! Also I had an IUD in and it fell out about 6 weeks ago. I took this as a sign, but he's being super careful about not getting me pregnant. What should I say/do?