Mobile development

I need an Android App. I would like it designed and built. I would like it to be simple with nice & elegant design so that students can chat with me and book a class with me and pay for it through app. Examples: Hashlearn, Vedantu on playstore but here I am only the single teacher for teaching Science to primary grade and Biology till college grade. Registration can be done only by student from all over the world with email or phone no. whatever you think will be best for me. registration from tutor is not required as I will be the only tutor in this app. Student should be able to select Science or Biology Subject. Then options for boards like cbse/ap/icse should come. then class etc. Instant doubt through chat with payment per question. Student should be to post pics from their book or screnshots etc. Students can request for a class with me which is done on skype. Class can be instant or scheduled for say 15 mins/30 mins/45 mins or 1 hr or it can monthly tuitions or unlimited instant doubt clearance etc. Please place bids accordingly as I am House wife and freelancer and single tutor and I will be owing my Mobile App. Its is my start-up venture.