What should I do?

Sarah • Babygirl born 10.10.15 Due with #2
So, according to Glow I'm 11dpo, but according to Fertility Friend I'm 12dpo. Either way, I tested this AM & it was BFN. Also, my BBT went from 98 to 97.9. January 1st will be a year (& I know many women have been TTC much longer). AF is due the 31st. I was on Letrozole this cycle & last - my bloodwork confirms ovulation. OB said if I'm not pregnant, I can do one more cycle of Letrozole before a specialist. When AF comes, do I use my last cycle of Letrozole or just take a break from it all? DH wants to try it again, but I'm so defeated already, I'm worried it won't work again & I'll feel even worse. He's been checked - he's  fine, I've had all the bloodwork & HSG - I don't ovulate naturally. We can't afford a specialist, so I'm just looking for advice on what to do. Thanks for the support, ladies.