Android Mobile App for Mental Wellbeing

I'm looking for an experienced Android developer to build a custom mobile app with the goal of promoting mental wellbeing for adolescents and teenagers. The app should have a professional and corporate design, and features should include meditation exercises, a mood tracker, guided breathing exercises, community based matching of user profiles, group chat, and 1:1 chat. Clean and minimalist layouts are preferred. The developer should have an excellent portfolio of high quality apps that are appropriate for the target demographic. I'm open to suggestions for any additional features that could be included in the app. I'm looking for a comprehensive and cost-effective solution.