Hi me and my parter had sex 1 week ago.
Yesterday morning I started feeling sick in the belly like I wanted to throw up and same today
I was supposed to get my period 3 days ago
Would I be pregnant?

Possibly.

ANY time there is penile insertion there is the possibility of pregnancy. But it is too soon for the nausea to be a symptom of pregnancy. There is no way for us to tell if you are or you are not. Since you are 3 days late you need to wait another 10 days and you can start using HPTs.