Baby Fever👶🏼

Hope • 18. Madly in love with my boyfriend. Very friendly and willing to make new friends & share my personal stories!
Soo... I'm 18, going on 19 in a few months and just graduated this past May but I have a bad case of baby fever that comes and goes, as well as my boyfriend. We've tried and "accidentally tried" but he believes he's sterile. Is there anyone who knows any ideas on what he can do, medically or any ideas, aside from keep trying?