Need Advice - How Long?

AF was due January 8th, and it still hasn't arrived. I've taken 3 hpt's, and had a blood test on 01/13, all were negative. I saw my new OBGYN last Friday. She said to take another test this week if AF hadn't started by Monday = BFN.

I'm now 23 days late, never have been late more than 2 days except when pregnant with my daughter.

So... how long do I wait until calling my doctor to see what the issue may be? Do I just wait until AF comes a month from now? Wait another week? I'm just curious to see if anyone has experienced this and has some suggestions.

Thanks!