The uterus is actually "hanging" in 2 large and 2-3 smaller ligamnets. Remember that it now is stretched way up higher than normal, and thus all those ligamnets start hurting as well.
And unfortunatelty, they are also attached to everywhere else in the lower abdomen, just about to every major bone, so they hurt as well.
It will get better soon, though, when they get stretched out and adapt. You are just experiencing the growth spurt of the pregnancy right now.