Negative pregnancy tests, but still no period. 🙄

So, I have never had a regular period, but I always try and keep track anyway. As of right now, my period is 16 days late from what it should have possibly been. It has never been this late before. I've taken multiple pregnancy tests, and they've all said negative. So of course I thought I wasn't pregnant. I was talking to my sister about it yesterday, and she reminded me that whenever she was pregnant with my niece, all her at home pregnancy tests said negative too. Should I wait a little longer and see what happens, or go ahead and go to the doctor?