Is there something mentally wrong with me or is this just the way i am?

Ok, im 14 turning 15 in august, and im wondering if there is something mentally wrong with me. Im very responsible, and pretty mature, but i feel like im split in two, like im two different people. One half is a normal teenager obsessed with my image and boys and starting to think about sex and makeup and crap like that, but the other half, my dominant half, is literally like an 8 year old girly girl. I love playing with my American Girl dolls still, i buy clothes for them and my Bitty Baby doll, and i still play with my littlest pet shops and my pokemon figures and my buildabears and my webkibnz. I still buy more of all of them!! I especially love fairies, more specifically disney fairies, i have two posters of them and the big barbie sized dolls of all the disney fairies and the little 5 inch fairies too! I love all my toys and i love to play and imagine and create and do everything a little 8 year old girl would do!! Is there something mentally wrong with me??? Is there a medical reason im like two different people??? My friends dont care at all and still love me and everything, but it does worry me there might be something wrong with me!! :(