Mobile App Development

I need an Android, iOS and windows app. Can start with android. I would like it designed and built. We have an app for Biotechnologyforums created by a third party, whom we have to pay monthly charges to keep the app up. But, that has restricted us to access the source files and no control over making updates and sending push notifications etc. And being a template based app, there are very limited features in the same. We want an app that we can publish ourselves and control ourselves and have following features: 1. All current features of the app. Our current app has all minimal basic features that must exist in a forum app. 2. A messenger/ chat system that can enable forum buddies to chat with each other. There should also be a provision like WhatsApp, where app users having contact numbers of each other can chat with each other and also add themselves as buddies on forum. 3. Registration using google /Facebook accounts. 4. App should be compatible with all android versions. 5. Better design layout (surprise me!) 6. Likes, pokes, images, videos, surveys, events We are making transition to a social network, without loosing our image and functionality as a forum. Looking forward