Help? I need to email last weeks worth of calls, texts, photos etc from a family shared phone plan

I’m on my brothers At&t cell phone service plan. I have some access to things on it but not full access to everything. I tried to download the At&t app and get into the account to get copies of what I need and email them but evidently my brother already has an account this way so I couldn’t access it. My car was stolen Sunday. My insurance company wants the last weeks worth of my phone calls and texts, pictures etc. to make sure I didn’t ya know try to get rid of my car for the insurance $ myself. I do not want my brother to know my car was stolen! The local PD are very close on the tail of finding my car! They almost had it last night. The guy stole it, forged my name on the title and sold it to this lady. She then went and paid the taxes and put the car title in her name. So she’s gonna be crushed when she finds out she bought a stolen car! Well. I cannot gain access to the account # and access my last weeks phone calls, texts, pictures etc. how do I do that? So I can email them to my insurance company. I really do not want my big brother knowing my car got stolen right out from beneath me like that.