Well she is a very sexual woman and if she's not dating anyone I'm sure she is...wanting...and yours truly will forever have an edge with her in that department. There is a method to my madness!
You were in the same bed, in the same room while she was changing, she took off her bra while you gave her a back rub. If what you say above is true something is not adding up. Either you're really good at blowing your own horn or she's really not in to you at all other than just being friends.
Time to man up and put an end to this excruciating madness once and for all. Time to man up!