When did I become a “Ma’am”?

You never realize how time can fly,
And for women, it’s just two words.
It’s hard to explain how time can change names
So I won’t even try.

 But can someone please tell me this
 When does Miss end and Ma’am begin?

I was a Miss for the longest time, even after I wed.
But as time went by, the word Miss faded away
I was now starting to be called a Ma’am,
and the term “Miss” was pure passé.

I started college rather late in life.
The students were mostly teens.. 
To me that was no bother.
Until one day a student stopped me and said:
“Ma’am, aren’t you LeAnne’s mother?”

Went to a restaurant with my husband to eat.
Noticed the prices were a little low.
 Asked the waitress about it, and she replied
“Ma’am, that’s the senior citizen’s rate”

When did I become a “Ma’am”?