Scientifically backed mental age test?

Does it exist? I'm 24 chronologically but I am for sure not functioning like one. Juvenile hobbies (youtube, nintendo games, mtg) picky eater, virgin, no driver's license, no college, very needy and attention seeking, emotionally unhinged, etc.

I asked my mother for her honest opinion and she said I might be 13-15 mentally. I would agree. But self-diagnosis is kinda cringe... Is there some way of formally testing for it? I'm not talking about random BuzzFeed style quizzes here. I've never heard of anything like that before, but I would be VERY interested in getting a professional opinion.