It's normal. For a few months after stopping BC, I had really erratic bleeding.
As you know, when BC pills work properly the hormones mimic pregnancy, thus you do not ovulate and can not become pregnant. So, your body has spent the last however many months being "tricked" into thinking you were pregnant, and now your body is like, "Hey, where did all those hormones go??".
Also, the "periods" we experience while on the pill are not true periods; they are breakthrough bleeding due to the hormone fluctuations during the one week each month where we do not take the pill (or take the placebos). From the time span you describe, it sounds like this is your first "real" period since stopping BC. It could also just be more breakthrough bleeding, but only your ovaries know for sure!
In any event, remember that a "real" period is heavier and longer than the "fake" ones you have while on the pill, so don't be alarmed. Also, remember your old friend "menstrual cramps"? She may come a callin' soon. I've found that taking Evening Primrose Oil capsules all month long both regulated my cycles and reduced cramps.
Good luck on the baby-making! ;-)