Late period and negative test!!

Katelyn • Married mom of 4 girls hoping that this last baby we have will be a boy but if not we will love a girl just as much!! :
I stopped birthcontrol (nuvaring) inJanuary after being on it a little over 2 years! We have been ttc since and I had my af on febuary 14th and was 3 days late that cycle which made it a 31 day cycle... Glow said i was due to start on march 14th but that was with a 28 day cycle.. With a 31 day cycle i was due to have af on tuesday march 17th and still no sign of af... I am on day 35 of this cycle with 3 negative pregnancy tests!? Any ideas? Im gonna call the dr monday if i still havent gotten a visit from af!!