I want to experiment with my best-friend...what should I do? (both girls)?

Ok, soo idk what it is lately but I think I'm falling for my bestie :( . Ive noticed that lately I have been thinking about her constantly and I often wonder if she feels the same way. Especially now since shes got a boyfriend it seems at though the feelings have only gotten stronger, like Ive became more dominant in showing my affection for her somehow! For example last weekend I was hanging out with her at wal-mart and she suddenly wraps her arms around my neck and cuddles her head into my shoulder(shes shorter then me btw) I responded by wrapping my arms around her waist and we stayed like that for like 10 mins...I'm pretty sure ppl walking by umed we were s judging by the position we were in :/? Later that night when I was sleeping over we had a very deep conversation while laying in bed together (about what I cant remember) after we stopped talking she said "I'd hug you right now..but that would be gay" I laughed smiled and said "Yea..I'd slap you if you did that" we both laughed! (but I mentally cursed myself because I"d actually be up for it, if she was interested and it sounded like she was a lil bit but I totally cut her off because I didn't know how to react at the Moment?) Anyway, I woke up the next mourning with her so close to me I felt her breathing on me, I mean if I inched a little closer I'd be kissing her! Normally we don't act very intimate towards each other or maybe its because I'm just not a naturally affectionate person and its hard for me to show emotions besides anger...smh. But as of late she's been more and more attentive toward me by leaning on my shoulder while we're watching a movie or playing in my hair things like that. I just find this weird because I'm not used to seeing this side of her, plus she has a boyfriend to do all this stuff with...so why me and why now all of the sudden? And also how do you think I could've handled the cuddling in bed situation a bit differently? Like what do you think I could have said in a clever way to initiate that I take the idea of cuddling with her seriously? Also, she's kissed girls and made out with them before, soo I know she's not phobic anything but she claims shes straight *shrugs* I'm confused about this because if she was soo straight laced then why kiss girls...plus it's not like I've exactly came out of the closet to her or anything so why is she testing me in that manner.(of course she's never seen me with a boyfriend in the 4 yrs she's known me) Do you think she she knows of my uality...that I'm a lil bi-curious and up for experimenting with her...idk I'm just confused!! And what do you think I could do to bring up to her or to show I like her but not exactly telling with words? Of course I wanna wait til were in collage together and were roomies (were going to the same university btw) be4 I try anything because shes still has a boyfriend and they're getting kinda serious...or maybe I won't try anything at all to save ruining a good friendship its hard to tell with her(maybe these feelings shall p)...Soo I know this was loong but I had to explain everything sorry....Well what do you think I should do you guys?