Ottomans - preventing coalitions?

So I'm playing as Ottomans, and I've got a bit of an issue - trying to push into the Balkans and Hungary is giving me a headache. If I leave him alone, he comes in and eats up wallachia and Bosnia. If I war him and annex croatia for the "push into the north" mission, all of Europe coalitions me (including my allies for some reason) and does a punitive war. If I don't take provinces, then it's just the same problem as if I leave him alone, only I can't war him for a while. I can't take Croatia from him, if I force him to release them they still won't become my vassal cos they're too developed so I'm gonna have to annex them sooner or later.

I'm not sure what I'm supposed to do here? Seems like I basically have no choice but to wait for like 50 years for my AE to go down and then try again, is that right?