Am still mummy to my eldest son, aged almost 16! In front of his friends too and no one bats an eyelid.
To DD, almost 14, I am mummy or mother.
To ds2 (9) I am sometimes mummy but usually mama.
My kids have never called me mum (their choice, although I must say I prefer mummy) but if any of them are talking about me I am mum ie "I'll ask my mum".
Their father has only ever been daddy.