Does she like me? Getting mixed signals.?

Alright, first of all.. I've had my suspicions that this girl has liked me for a while. More interesingly, she's my best friend's sister.. Anyways.. everytime I come over to his house, the FIRST thing she always asks is "How's your girlfriend doing?". Normal enough.. She also gives me treatment different than any of her brother's other friends.. She'll randomly hug me, call me "Sammy" when i go by Sam.. She'll randomly lay her head down on my lap when im watching TV, she leans against me, flirts with me.. When I first got into my current relationship, she jokingly said "You know, i'm really heartbroken that you're taken now." Okay, so at this point, you'd think it'd be a no brainer right? Well, at one point my curiousity got the better of me, so I said to her basically "I heard people saying you had a thing for me." And she replied with "I dont know where you heard that, but I dont like you like that. Just as family." Everyone else tells me that she likes me, so confusing. Any help?