No Period Since December

I'm 18 never been pregnant I live with my partner but every pregnancy test I take is negative even at the doctor's my last period was December 6th and the OB isnt taking appointments till june bc of covid19 and I'm worried that I wont be able to have kids my periods never been this late but it's always been a little irregular I'd crank when I had my period but not extremely bad I don't know what to do I've tried my best not to worry but idk what to do anymore especially if I don't have a period by june