how can I make sure about my phone is this from apple.com or another seller?

Apple Support Community Forum

This is Apple Support Community forum, for user to user interaction for information & idea sharing between users, if need be, extend support on technical knowhow in handling Apple products from more experienced fellow user, This is not the right forum to discuss with Apple Inc.

This is a user to user forum and Apple is not here. If you have a question about your phone order, you need to contact Apple directly for help with that.