I personally wouldn't want to go out with (or have sex with a girl under 19) because I'd feel like a pervert or feel like its socially unacceptable and people would look down on me so I wouldn't do it.
theres a girl I know thats 17 at my work and I think she likes me but I try to stay away from her at work because I feel embarrassed looking like i'm hitting on a 17 year old when i'm 24 (even worse if you're 40). Still she keeps on following me around at work and she made some sexual remarks to me a couple of times which made me feel really creepy even though she said it. Like I was eating a bannana and she is sitting next to me and she says " I really like big bannanas" I was like wtf??? and this other time I was eating a popsicle and she says " I like to suck on creamy things" I'm not making this up she said that and I was like shit I got to get away from her she's making me feel like a creep. I think she's just saying that shit because I ignore her and she's trying to ge my attention.
like I said I may think a 16-17 year old is 'hot' but I wouldn't sleep with them or go out them because even if its not really "wrong" its not really socially acceptable and people would look at me like i'm a perv and talk shit about me behind my back.
I don't see anything wrong with 18+ though.
you should give her your popsicle when she turns 18.