I need a software architect developer.

We are creating a dating cum matrimonial cum make friends app in android, iOS and web versions. We need to calculate cloud costs for our app to include in business plan and that depends on the architecture of the app.

So we need help in designing the architecture of the app and calculate the cloud costs for the app for 2000 test profiles, 2000 test profiles plus 0.5 million users, 2000 test profiles plus 3 million users and 2000 test profiles plus 10 million users.

Please help.