Could I be pregnant?

Luisa • MissyB1309💋
My boyfriend and I have been having unprotected sex without any form of birth control trying but not really trying to get pregnant. Anyways, I took a hair skin and nails vitamin in the am and then shortly after felt nauseous and threw up. 
Could I be pregnant? I dont feel pregnant. I have 2 daughters and I remember what the early symptoms were and felt like, but I don't feel much or any at all. Also, my period is 4 days late and I took out my IUD 3 months ago.  Thoughts?