The pill can keep hormones a basically even levels while a woman is on them as recommended. Normally hormones fluctuate a lot over the course of a month. I think that the emotional roller coaster that can accompany coming off that hormone regulation can be surprising to a woman who hasnt experienced it in a while. And it could take a while to really get them all out of her system, maybe 2 or 3 months to get back to "normal mode".
Has she been on the birth control since you knew her? Maybe this is part of her hormone cycles. Shes been off them for a while now, I wouldnt blame it on the pills so much anymore.
Now, what concerns me even more: You snooped on a woman who thinks you are a jealous man? NO, NO, NO! Thats exactly what you would expect a jealous person to do...
Make some changes for yourself, ask her how you could show her that you arent jealous. And for godsakes, stop snooping. Can you plan a special camping trip or something? If you are having issues with your M, I think that maybe now might not be the best time to be trying to conceive.
I guess I gave the wrong finger to the wrong man...