15 days late

Hello everyone.

I'm 15 days late for my monthly AF visit, with no signs that she is coming anytime soon.

I took a hpt 4 days after AF was expected and got a bfp. Then took another hpt 2 days after the first and got a bfn.

It's been 9 days since my last hpt and still nothing, but I don't know if I want to test again or not because I feel like every bfn is a waste of a test (plus it is a pretty big disappointment each time).

How long should I wait for AF before testing again? Or going to my doctor?