Has this happen to anyone ?

My periods are on time every month because I been keeping track for years even more when I found out I had uterine fibroids so if anything goes on different I will know so I have been trying to have a baby for the last three months now I am 15 days late so I took a pregnancy test came out negivtive all 4 test I took then I want to the doctor that urine test was negative too doctor said that I had thyroid problem but that don't make sense because I'm on time every month so I asked if they could do a blood test to make sure I will know Monday has this happen to anyone else?