My traveling companion has gone missing. I think I may have told her to wait somewhere but I can't really remember if I did or not. I can't get any more companions because they just tell me that it looks like I have some one already. So is there anyway to find her?

if you are on pc, you can use console commands. otherwise after 3 days she'll get sick of waiting and go back to where you first recruited her.

If your on the PC you can use the console command to move to your companion if you know its code. The command is:

player.moveto code goes here

If you need to find the code look for your follower http://www.uesp.net/wiki/Skyrim:Followers . Click on its name and you can look up the codes.