If you contact them saying the account might be hacked as you never had an email starting with a b, then you need to provide them with enough information to proof the account belongs to you. This needs to be information you can not find out by just looking at the user lookup.
things as: neofriends, NC purchases (If you have these, it will really help!), rare items codes you've claimed, neopets you created and as what species/color, equipment they might own/have equiped, battledome abilities, closet items, books, avatars you won, login locations (IP address), favorite games to play, etc
Basically anything you can think of that only the owner knows.
I've gotten my account back that way, fairly quickly too I must say. I did have a habit of making lists of almost everything so I knew a lot about my account, and like I said, having purchased NC in the past helped a lot too as I could provide proof of my visa.
Don't give up, it's worth a try!