Fallout 3 Star Paladin Cross Lost?

I had Cross as my first follower, then went and found dad at the garage. After I started to follow him to Rivit City, she was gone! I went back to look at the garage, and at the citadel. I still can't find her. The only reason I need her now is because I have Charon's contract now and he won't join me because he says my party is too big. Where did she go??? (This is on xbox).