Mixed signals are always a red flag.
Although some chicks do use (dumb) tactics like "this guy asked me out" or other stuff like flirting with other guys to make a guy jealous and try to spur him into making a move, it is the speciality of young, immature chicks and game players.
A chick who is genuinely into you will not blow hot and cold, she will MAKE IT EASY for you - provide you opportunities to ask her out. You say she loves your attention, but she hardly ever talks to you when your friends are around. So if what happens is that when other guys are around she gets attention off them instead, then you know you're nothing special to her (i.e. your attention is what she craves, NOT you).
Imagine it like a car needing gas - it doesn't matter what filling station you get it from, so long as you get it (it's a commodity, it all has the same effect). Gas is the fuel of a car as attention is the fuel of an AW - fuel for her ego.
Although you provided little info, you seeingly called it already saying she craves your attention, this chick is likely an attention wh0re. If you really want to know the situation (and get some closure before you risk oneitis), ask her out on a one-on-one date and try to kiss her on the lips - if either fails, she is just a game playing AW. If that happens you MUST drop any thoughts of you and her together because once you've definitively shown your interest by asking her out she will dangle the carrot in front of you forever and lead you on for as long as you let her.
I'm betting she's just an AW and you won't get anywhere here.
It's THAT EASY!