Fertility!!!

Okay so my bf and I have been having unprotected sex for a little over a year and a half. I’ve been to the OBGYN just to check and see if everything is working. She said my vitamin B and D was a little low but everything else looked fine! So I know there are people who have had unprotected sex for over a year or a year and not gotten pregnant, I just want to know is there anything y’all figured out! Any problems? Anything else it could be?! Just curious ☺️