Being friendzoned is a closer in 99% of guy's situations, OP. Besides, you even said it yourself: you're both best friends. So why are you expecting more from her?
Protip (from experience): as soon as the whole 'friends' thing is brought up, and you think you want more, say so. Otherwise she'll never develop the spark for you and will always think of you as one. You should've spoken sooner. It's too late, so move on.
I missed my opportunity with one of my 'best female friends' because I was a puss that didn't speak up when I should've (and I was clearly skipping choice opportunities to do something...we were basically a perfect match). She found another guy, and I tried making a move then because I feared I was going to lose my chance; I did. She said she wanted a guy to let her know right away if he had feelings for her.
Past: '08 E92 335i|JB|wheels|"eater of HPFPs"
Present:'15 Mustang GT|401A|PP|Recaros|6MT
Sig pic unrelated. I like to go sideways and stuff.