Chris,
How a woman reacts to the change in hormone that pregnancy brings dictates how severe and when symptoms like nausea occur.
Some women experience symptoms very early when there would be little hcg and other women (like me!) experience very little nausea at all. The progesterone levels of the second half of your cycle can sometimes produce nausea for some women too...
I hope you have conceived a little munchkin - please keep us posted.