2 periods a month on Lyza, now nothing, pregnant?

[Ohmissfaith]

I have been on a new combination birth control that's supposed to stop my periods. It's Lyza. The first month I had my normal period. The second I bled all month long. The next 2 months I had two full on cramping painful periods in a month each time. Now this month, I haven't gotten my period at the normal time or the 2nd period my birth control caused. I'm a day past when my second period should have ended. I take my pills pretty consistently. There's a couple days I was about 3 hours late. But I didn't think it would hugely affect my birth control. My breasts are extremely tinder, my back has been hurting a ridiculous amount and I've been the appropriate amount of pms emotional. But I took a pregnancy test this morning and it came back negative. Could I be pregnant or is my birth control finally working?