No period :(

So in August and September my periods were late (august was 8 days) September was a few days. Went to doctor she said about tracking them I did ( I should mention I did have negative pregnancy tests) now I'm 12 days late, I was at the dr yesterday but I was too late to go for blood clinic so have to go Monday. I am treated for under active thyroid. I have been sleepy lately and headaches and had acne last week as if I had my period. Anyone else have this happen ?