Sad that it'll never happen

Ok so my SO and I have been going unprotected since Feb of 2017. We haven't started trying until like a week ago. Up until that time, he was barely eating due to not having a lot of money and his cum wasn't plentiful. We've been eating more since December since I got a new job! My periods stopped for a while then came back once I got on thyroid meds. Lost some weight and thought I started my period on the 5th of this month cause there was light blood but nothing has shown since then. Took a pregnancy test on the 5th and before then and negative. I've been emotional for a couple weeks now, just crying over nothing. I was also sick for 2 weeks so maybe that has to do with it as well, but I'm worried my periods will disappear again and that us having a baby will never happen