Pregnant?

Hey mommas! I’m about 4 months post partum. I’m breastfeeding and I’m on the mini pill. I missed a few nights of my pill but I got back on it the last few days. I’ve had some light bleeding, a very bad headache and I feel so sick like throwing up. Is this just from the few days I got off the pill or could I be pregnant? We did have sex around the time.