My boy said he could get me a Beta invite for Cata, and this morning a new account showed up on my battle.net called WoW1 PTR. I'm a little confused though because when I try to install it puts a launcher for WotLK and says nothing about Cata. Am I going about this the wrong way or did I even get a beta invite yet at all?
It doesn't look like you are flagged for the beta. As others have mentioned, the PTR is not beta it is a test realm for upcoming patches. I would recommend following up with your son about this issue.
Let us know if you have any additional questions. Thanks!