How does one "act their age"? Am I "immature"?

I am in my twenties and have a child of my own, I work with children as well and admit I act goofy and silly sometimes (thats always been my character)...some people have commented saying I act like I'm in highschool and I talk like a "valley girl"...someone recently told me I get overly excited over things--"like a highschool girl"--their exact words...I just really try to stay positive and happy (even though there I times I fake it as I battle with depression)...yet at the same time I don't see the problem with being "youthful" and staying "young" in a sense...I am starting to wonder if something is wrong with me??