missed period??

hi all, need some advice! so i’ve currently missed 2 whole periods, (eve says i’m 30 days late) and i’m not sure why. i’ve taken pregnancy tests and they all came back negative, i’m not under any major stress and i haven’t been sick. i’m going to the doctor next week but i’m hoping someone else has been through this that can calm my nerves😅 (i also had my daughter in december but my periods have been regular the past 6 months after i stopped breastfeeding)