My number in iMessage and face time

Settings﹥Messages﹥Send & Receive﹥Start new conversation from﹥(select phone number instead of ID or email)

Settings﹥FaceTime﹥Caller ID﹥(select phone number instead of ID or email)

This may not influence current conversations, or conversations initiated by others from existing details in their Contacts list regarding you. You may have to ask them to remove that address from their contact list.

it keeps loading

That is not normal when connected to a good network (cellular data or Wi-Fi). Has this number been authenticated/verified for Apple ID use? Go to appleid.apple.com to check and –if needed– verify the number (it will send a message that requires a timely response).

If it still won’t make the setting, try restarting the iPhone.

Should I update to iOS 11.4.1 to overcome this silly problem.

A fresh install of the OS or a Restore to factory settings can solve certain problems, but this was not a known issue prior to 11.4.1.