I'm so sorry to hear you're going through this. Waiting is often the hardest part of this whole process! I encourage you to be (politely) assertive and review the steps you've already taken when you talk to the scheduling people. Sometimes they'll be empathetic and try to get you in sooner.
It's not their fault - they book so many appointments it just becomes kind of mechanical for them. But seriously - for the long haul consider getting your treatment at a larger hospital or cancer center. They really do make things easier for you - it's almost like they have their own process and pace, different from other medical specialties. They get that waiting is hard, and they really try to calm your fears. Good luck.......hope it all starts getting easier for you!