Removal of the right breast was so it didn't get in the way of using bow and arrow, as far as I can remember. Bit of a bugger if you are left handed?
I am assuming that the guys saying this are thinking of Xenia and mean it as a complement, lol, I had a quick gander at your site and if someone had described you as amazonian to me I would have been very dissapointed, you are too pretty and petite to fit that description.
This is what I picture when someone talks about an amazonian woman
http://heim.ifi.uio.no/~thomas/lists/images/caldwell01.jpg