Don't Want To Disappoint

Hi im.new to all this, my partner and i decided we are ready to have a baby together. Hes so happy and honestly never meet a guy so good with kids he would be a greay father. Hes 1 of 10 siblings in his family so has a MASSIVE family. I told him we can try and have been for a few months now but no luck. I was told a while back that chance i cant have children and he knows that but now its got to the point i won't do any tests cause im afraid i keep letting him down. Does anyone out there understand or have advice?