Can't access family sharing

Hi,

I've set up a family on my prevues device (iphone 7).

Now i'm trying to manage my family subscription but when trying to click on family sharing on my iphone settings, it gives me the following error:

"Mush...@gmail.com" is already used for shared purchases in Moshe Salamon's family. Ask Moshe to send you invitation to join family sharing.

the problem is that i am "Moshe Salamon" and Mush...@gmail.com is my email account which actually used on this device as the apple ID.

for some reason my iphone doesn't do this connection.

I'm using iphone 8, iOS 11.2

I own mac air as well, icloud/"manage family" option is blocked for some reason.

Thanks,

Mush