my phone number

okay so i transfered from an iphone 7 to an iphone 11 and now i cant text people unless i use my email even though my number is linked to this phone, when i go to settings and try to click my number instead of email in send and receive it doesnt work. ive tried to power my phone off and on but it still isnt working and now the number on send and receive is showing up as my email and my brothers number, we both got phones at the same time but we arent on the same bill and our phones arent linked in any way. what do i do?