missing period?

Hey mamas- I gave birth to my little girl 10/1. I had about 4 weeks of bleeding and then had a normal period in November and another in December, now I’m 7 days late. I a little concerned because my period is almost never late and if it is never more then 2 days. I have taken 3 tests all negative. Also worried maybe I’m going to start going through my “changes” but I feel a little to young for that I’m just about to turn 30. Any other mamas have this happen? How did it turn out pregnant or not? (Side note yes I have had unprotected sex with hubby we always use withdrawal method- have been for a long time and only ever got pregnant when we wanted to I know it’s not a reliable was not to conceive but it has always worked for us and if I’m pregnant that’s okay just a little concerned where aunt flow is)