I had this problem in role reversal, there was a girl who i liked three floors down from me, i used to go down stairs and talk to her alot. made excuses up all the time, just to get down to that floor,
id even go for a coffee at the coffee house across the road when i knew she was going, accidentally of course.
We got on fine for several months, conversations were good but not really that frequent unfortunatley.
I lost a bit of interest to be honest (i didnt think anything would come of it) but little did i know that she was in the same predicament that you are currently in.
She really liked me but i had no idea. I missed several of the hints that were thrown at me, (that maybe cos im a natural flirt anyway)
Alot of what your saying sounds really familiar.
I eventually found out that she liked me at a party which someone at work had for a wedding.
it was soooo...... immature.
i was only talking to one of her friends who happens to be a bit of a tomboy (and a good friend of mine) when she declared her friends desire for me.
what happened next was the WRONG way to go about it.
Getting drunk and getting it on, on the dancefloor for everybody to see.
The pressure at work for weeks later was incredible.
So i urge you not to make that mistake,