Calling me a little girl! I’m 24 years old!!

So as you read from the title I am 24 years old. The place that I work at they keep calling me a little girl and it’s really getting on my nerves. They are a lot older than me I would say they range from there late 30s to 60s. Maybe it’s because I look really young and I am the youngest l. But I think it’s really disrespectful how they keep calling me that. After I said I don’t like being called a “little girl.” I told one of them y’all wouldn’t like it if I called y’all old. Then she said no we wouldn’t. But then stop calling me something I am not. But they think it’s funny though but it’s not funny!