New TTC concerns

Ki
My boyfriend and I are in a fairly new relationship, we just know we are meant to be. He's my soulmate. 
We aren't explicitly trying to conceive but we would be extatic if I were to get pregnant. 
That being said, he's came in me about 5 times in the past week and a half. I've taken two tests and both are negative. However, tonight I became super nauseous in the car and then started to get a headache. 
Any ideas what this could mean? Pretty sure I wouldn't be feeling morning sickness this soon but it would be my first child so I'm not entirely sure what to expect.