Tww has become a 3ww

Lindsay
So here I am still waiting. I have very regular cycles (29 days) that always start on time. I'm never late and I never miss a period. Well.... Until now. I'm officially 1 week late. I'm 21 dpo and cd 36 and still all hpts are bfn! At this point I wish af would show her ugly face or that an hot would come back bfp
My only symptoms are extreme fatigue and lower back pain and of course no period and my bbt has stayed high. I'm just curious, am I pregnant or is there some other explanation as to why my period is mia w high bbt? I have never not ovulated in a cycle either.
Any and all advice would be great. My dr said to wait a couple more days and test again. So come Monday if still no af or bfp I'll be calling them back. I'm just confused and sort of worried. Help?!