My mom occasionally refers to me as her baby, though it's much less frequent since I turned 18 and moved to college. Largely, it comes in her occasional "I'm so proud of you" tangents, so I don't mind them much. By and large, I'm treated as an adult. I'd be offended if my mother referred to me seriously as a "boy" at your age (provided she wasn't joking. We do that back and forth a lot).

I'm sorry to hear about your mother Lovebirds. You certainly deserve a lot more than an apology from her.