No AF, 3 months in.

Hi guys! 

i finished my CP mid way through the pack (silly I know) and had a withdrawal bleed a couple of days after as expected (6th dec 17) and since Then I’ve had nothing. A cramp here and there but no bleeding or spotting or anything. I’m worried as TTC and ive heard you can conceive before your first period as it depends whether ovulation comes first or AF. FYI, was on Dianetre without a break for 10years! Any help would be appreciated should I be more concerned than I am? the Doc said totally normal but can’t help but worry!! Thanks