Hmm...
I'm inclined to think it's not your BBT if it's not showing the same temp no matter what time of day, ya know?
I see you've only got 1 posting, so you can't post a link to your chart until you've got 10 postings... But I'd love to take a look at it once you've got enough posts to show it to us.
I know I've had flat temps before where my BBT seemed to fall in love with a certain temp, and it all worked out fine... but then again, without seeing your chart, it's a bit tougher to say exactly what may be happening.