Besides pregnancy, has your period ever been 10+ days late?

I have taken five at home tests and a blood test at the doctor and nothing. I am so confused! I am usually so regular I even know to go to bed wearing a pad and my period undies the night it’s supposed to start because it ALWAYS does. Was there ever a time yours was this late for nonpregnancy related reasons? (I have a doctor’s appointment Friday, btw!)