There's nothing wrong with reading the books, but be sure you're being honest with yourself about what the attraction of these books is.
I was at an Aspie Support Group the other day, and one of the people (female) made a comment about how we Aspies often can't relate to people our own age, and tend to relate better to younger people. And reading novels is one way we learn about people, about ways to live our lives. And, of course, we Aspie guys tend to find girls a complete mystery So maybe you're just trying to find out about people you'd like to be friends with.
I went through something similar myself... one of my first jobs was shelving books at the library, and at some point I just wanted to read some of those "girl books." Of course, "Are You There God It's Me Margaret" may have been a somewhat creepy first choice, but... it was a way to get a peek into a world I otherwise felt shut out of...
The one thing you might need to be careful about is the whole thing of older guys and younger girls... you're a little bit on one side of the border line, and if you find yourself thinking of girls on the other side of that line as girlfriend material... well, just be careful out there. As the saying goes, "fifteen will get you twenty, five will get you life."