Why is my girlfriend doing this? 10 points?

ok so my GF and i are both 15 and have been going out for 3 months now. we started out as really good friends until i asked her out and she said yes she liked me cause i was "sweet and funny". we sometimes go to each others house and she almost always wants to cuddle on the couch she says im her " big cuddly teddy bear". she also likes to sit on my lap shes says im soft and comfy and she said to me "Santa Claus has got nothing on you" i thought that was funny. im 5'8 and 255 pounds so i know i am fat, but i am perfectly happy with who i am. and shes not fat at all she is a small girl shes 5'0 and im going to guess around 100 pounds, and she is super gorgeous. we sometimes playfully tease eachother about our size like i will tease about how short she is and she will tease about my weight but we both jave high self asteem and we know were just kidding. the only thing im curious about is when ever we hug and kiss she likes to grab on to and hold my fat rolls and love handles like yesterday when i came out of baseball practice and she came out of tennis practice she did that while we were hugging and kissing, also while we cuddle she likes to squeeze and rub my belly. really dont care that shes doing this. if anything i like that she does that feels good i guess. i guess im just curious. her past BF have been averaged sized, or muscular 6 pack guys im her first big BF