Hello Kai,
hm, your config looks ok.
You are saying that the XS Application is also not available anymore in the XS Applications tab. Maybe the issue is related to the problems reported in the HCP space for the trial instance (e.g. http://scn.sap.com/thread/3746068). I had the same issue today.
Perhaps you can try to create a new XS app for testing (and copy your files from the old project to the new one).
Best Regards,
Florian