Here's my chart overlay:
I didn't really convince myself of pregnancy each month, especially not by temps. I guess they were fairly boring and seemed to follow the same trend. The last one got me a little excited (combined with the fact that I was really fatigued and my sleeping schedule started to change at around 6 DPO... which was probably a day or two before implantation), but I *tried* not to get my hopes up. When I tested negative at 12 DPO, I knew that was wrong. The next day I got two BFPs and continued to get BFPs for a few more days.
So because the last one was so much different (combined with the fatigue), despite not wanting to get my hopes up, I *knew* I was pregnant.