I am 24 and I am a OTT Sweet Lolita. (Dunno if I should talk though since I am always mistaken for a 12-14 year old, no matter what I wear XD)
I don't think their is an age limit for Lolita and I don't care or worry about what other Lolitas think or say. I wear Lolita for myself, not for them. So I am going to keep wearing it until/if I get tired of it. I also don't believe in switching styles just because you are older, I am not a fan of classic styles and I only like some Gothic outfits but I am mostly a OTT Sweet lover. So I am not going to wear more "mature" styles like classic just becuase I am older or whatever.
Also about looking cute, doesn't have to do with age. As I said, at 24, I get mistaken for a 12-14 year old. Yet I have seen and mistaken girls who were in their teens for someone in their 20's. Also there is makeup tricks to look "cute" and doll like.
Though in the end, just wear what you like no matter how old you get ,others should not stop you for doing something that makes you happy. Yes their might be others who say you are too old but they tend to be elitists and snobs, people worth ignoring.