thoughts??

GF
When i first got my period i think i was 12 and it would come regular but since age 14 it started becoming irregular . Sometimes it would come super late(longest 3 months) and other times 2-3 days late. I had a baby in 2016 age 17 and my period was regular for 2 months after i gave birth but again started to be irregular. Right now I'm 54 days late and I've took pregnancy test which came out negative. I don't know what to think. Also I can't go to dr because i have no insurance and can't pay out of pocket because I'm pretty sure those visits aren't cheap! Any advice on what y'all think it could be will help! TIA