Is it possible for hormones to negate birth control pills?

Ok, here's the backstory, and it's happened three times now.

I've been on Loestrin 24 Fe for almost three years now, but have only recently become sexually active. I was put on birth control due to excessively heavy bleeding and really bad cramping that would leave me in bed for several days.

Anywho...

I haven't had any instances of breakthrough bleeding until recently. Usually we're somewhat active, but we don't really plan when we have sex, it just kind of happens, lol. The couple of times we have been able to plan something, however, despite my being in the middle of a pill pack, I will get more bleeding than when my pack ends and I menstruate.

Is it possible that I get so excited and anticipate our rendezvous enough that my hormones override the Loestrin and cause me to menstruate?

I'm going to ask my gyno next time I see her, but it doesn't seem to be anything worrying, just annoying when I can plan to get him all to myself, lol.