Disappointed...

I'm 17 and my boyfriend of a year is 21 we have been trying for a baby for 9 months now. We try any chance we get and we have sex quite a bit... when he finishes a lot of it comes out is there any suggestions on why that is or how I can help it? I really want a baby. It's the one thing that makes me happy and every time it's negative I get so disappointed.. I just... need suggestions....thanks...