No period AGAIN!!

Natalie

Up until 4th November 2017 I had no period for 6 months. Been trying for a baby but nothing. I have had 10 previous miscarriages all at 5/6 weeks and doctors have tested with bloods, scans etc and apparently nothing wrong! My sister has PCOS but has a 7 yr old. I was due again about 5 days ago to start my period and again it hasn’t come! What is happening?? Is there something wrong with me?! Any ideas? Thank you.