If you want to save money you need to realize that you're addicted to your phone and the expensive plan that AT&T is selling you. You can't get away from paying the price without losing some of the service. 90% of the things you list as "needing" you don't really need at all. For instance, music streaming, really? Ten years ago this service was nonexistent, and now this is something you absolutely cannot live without? Download some music from iTunes or Amazon, or just listen to the radio or birds chirping.
There are also lots of ways you can alter how you use your phone to reduce data consumption. For instance, forget Apple Maps and download an offline GPS navigation app like NavFree. In general, look for apps that can download and cache data when you're on WiFi so you can access it when you're on the road.