Losing Hope

We've been trying now for over a year and a half and nothing is happening. We have both had our first fertility tests and they have shown that we are both ok. My partner already has a son and sometimes I don't think he really understands how much this means to me. I'm 35 and he's 40 and I feel like my clock is ticking and I'm running out of time. Now to top it off I seem to be surrounded by pregnant people and don't mean to sound selfish but I can't help but be jealous of them.