3 years no baby

My boyfriend and I have been together for the past 3 years... we where using condoms or the pull out method at first so I wouldn’t get pregnant. Because I wasn’t ready he wasn’t ready... but guess what??? Now we are ready!!! And what so crazy is now I can’t seem to get pregnant! We haven’t used condoms and he hasn’t pulled out in almost a year 1/2. Is it something I’m doing wrong??? Am I just infertile?? Am if I am how do tell my significant other that I probably won’t be able to give us the kids we both wanted?? Help please