Is it possible for someone to be about 8 weeks pregnant and not test positive?

For almost every illness I've had I don't test positive until way way after I caught it. So it wouldn't be odd. But is it possible?!?!

I've had, what I believe to be, morning sickness all week. And I'm starting to bulge out a little. I'm growing and I've had a many MANY reasons to believe I am with child.

But the tests say different.

PLESAE POST IF THERE IS ANY CHANCE.

Also

Would it effect the baby's health if it was rape instead of normal intercourse?