Obviously, you are talking about the use of “boy/girl” in everyday use and not in the scene.

I personally believe the usage has morphed into current use from the idea that generally, women are concerned about aging and men are concerned about being experienced, particularly in their perception of being attractive to the opposite sex. I see many instances of women saying, “Don't call me 'ma'am,' it makes me sound/feel old.” Usually men don't mind being called 'sir' as they feel the maturity and experience implied by its use makes them more attractive than being youthful.

The use of 'girl' or 'boy' being offensive is mostly interpreted by context and/or intent. Generally the term when used to refer to adults implies attitude as well as actual age. By context or intent, it can be used to negatively imply low status and/or immaturity. It is in those cases, being offended is justified and correction is appropriate.

That may be due to your assertion of the obvious—they know you're a grown woman. Just the statement 'I'm not a girl' is enough to admonish the reference and they have to be outright rude to use it again.
I feel your “Please don't call me 'miss'. That's an honorific meant for young girls." comment also lectures them on the obvious and dilutes your objection. I would suggest something like, “I prefer Ms., thank you” would get the message across. The 'thank you' implies they will comply.

I hope my comments aren't inappropriate as I don't know the situations you've encountered. They are just honest thoughts I had when I read your post.

As to the use of 'good boy' in the context of the scene outside of a 'mommy' kind of scenario, I think it again depends on context and intent. It is condescending and a reflection of status. When I first encountered it, I really didn't like it. As time went on, the humiliation and reinforcement of the lower status in a F/m relationship became a turn-on.