morning nausea & late period

I keep getting really nauseous in the morning and idk why. It's not every single morning but most mornings for the last week or so. And not this weekend (it's Monday) but the weekend before my boyfriend and I had sex about 5 times all pull out method. We always clean after/ between and he'll go pee and such to get rid of pre cum. I am on birth control although a couple days later I missed a pill because I was busy. I'm also 2 days late of my period, which isn't a big deal as of now. The last three nights I've had weird dreams about breast feeding my kid in the dream, or just having a kid that happens to be mine. This morning I felt sick but he also feels sick so idk.