I am an experienced Unity3D games and augmented reality application developer, have three year experience of working on several project for companies and also one year experience for working on some of my Unity Asset Store packages ( Checkout my portfolio )
I have read about your requirements in your project post which I can deliver at the specified time.
Below i have created milestones for your ease to know what you will get for your money.
I have some questions also regarding to the requirements you specified , like you want an admin page add, edit and delete of question banks per level is that some online admin page ( which will make the app requires internet connection ) or admin page for users, also is it for some specific platform?
For further details and clarifications you can contact me through freelancer or on my email address.