I like being my best friend's "girl friend", but I want to be her boyfriend. How can I make this happen?

My best friend is a girl,Tara, and I am a boy. We are both 16 and have been friends for almost 3 years. About a year ago, I put on her cheerleading outfit as a joke (sort of, i'd been wanting to for a while). She thought I was really cute in it (we are actually close in size as I am 5'8 130lbs and she is 5'6 115lbs) so she put a wig on me and makeup and jewelry and really made me look like a girl. And we danced around the house. Her dad came home and asked her who her knew friend was (I'd been to her house and met her dad at least 30 times). She said "this is Danielle and she's new to my school" and he was really nice to me (which he never was when I was Marty). Anyway, we started doing this every few days or so. I bought fake to insert in a bra, undies that hide my junk, and shoes (because I wear size 10 women's and she is a size 7). Everything else I can wear of her's so we share. She loves to make me up and I love it as well. She has made me go to parties dressed up and I have danced with boys. I really like having them try to pick me up. I like slow dancing with them and feeling them touch my waist and and I like it when I feel them get excited when we slow dance. But I don't want more than that. Some have tried to kiss me and I don't like that. I only fantasize about having with girls, and especially with Tara. When we get dressed we are naked together and I have to hide because she is so beautiful and I get worked up. And I haven't been able to tell her this because I don't want to mess things up. I am so confused about what's going on. I don't want to stop cross dressing but I don't want to be a girl, and I'm definitely not gay. What's going on?