Good morning,
As a developer with strenght in the Android area, I consider I can help you the application you need, I currently own 3 apps published in the store, have plenty of knowledge in androids guidelines and the most commons widgets used in an app. You can check my portfolio and my profile to see more information of my projects if interested.
I understand that you will use amazon web services and tough I have experience in the use of web services, I still haven't tried the ones offered by amazon. Still that doesn't mean I'm not willing to learn new stuff.
If you have any question please ask without a doubt, I'll await your answer.
Thank you.