My wife and I had our Beta test today - its day 13 after transfer. (The Embryo's were 2d not 3d.) It was a BFN

Obviously were are very disappointed but not surprised, as she had bronchitis almost the entire 2ww
We tested today because we fly back home for a week to the UK tomorrow, which would've been day 14. (Currently living in Jeddah).
Doc was very hesitant to give me a number for the test and just said it was negative, but, that because she hadn't started her period, to continue taking the progesterone and estrogen whilst we are away because the result might change. This gave me a little hope, until I finally got the number from him... 0.336/ml!
This is our first IVF/ICSI and Im certainly no expert, but even I know that number sucks - especially on day 13!
My question is ... isn't the onset of AF being prevented by taking the progesterone? And if so what possible chance could there be with a beta score so low?
Very confused

Stephen