11 days late

Brittney
I'm now officially 11 days late on my period. Took multiple hpt with all negatives. Went to the doctor and got a blood test with a negative result. I'm not stressed haven't gained or lost any weight no new routain haven't been on birth control in 8 months... So what the hell?!?! I always have very regular periods. Could I be skipping a period or what? Has this happen to anyone else?