My best suggestion would be to trash all the different Gimps that you have downloaded, and start fresh. I use McGimp…you can download it from
Partha's Place. It is the first one on the list. It is compiled with quite a few useful Python plug-ins already in it and also, GMic is included. IIRC, when it downloaded to my Macbook, it self-installed, but there are instructions for installation at Parth's place that you probably should read in case you would need them.
P.S. I never downloaded the X11 or quartz, as you will not need them for Partha's version, and I don't think the new MacBooks need them. I still use Mountain Lion, I don't want to upgrade to Mavericks because some people say it doesn't play nice with Gimp.