60 days no period. 25 year old.

October 26th 2016 was the first day of my last period it lasted its usual 4 days and it came on day 35 after the end of my previous period. It's now Christmas eve 2016 and I've taken 3 pregnancy tests at different times during these last 60 days. All were negative I had my usual cravings for sweets around the time I was expecting my period. I'm not very stressed but I am starting my battle against BPD, anxiety, insomnia, and depression and I've had my thyroid medication dosage upped. People figure it's the thyroid medication but it's never effected my period before when I've had it upped in the past. Should I be worried? I plan to see a doctor after the holiday season because they are always booked full this time of year.