My tongue sticks out when I play flute!?

I've been playing flute for three years, and when I play, the two sides of my tongue kinda roll in toward the middle of my tongue, and the tip slightly sticks out of my lips. I've watched other people in my band class play flute, and I seem to be the only one with this problem. Most of the time, I produce really good tone quality, but once I get to higher notes, my damn tongue gets in the way and I can't hit the high notes as clearly as I would like to. Plus, it's just embarrassing. I hate when people watch me play, because even my friends who know nothing about flute know somethings wrong with my embouchure. So to any flute players out there, have you ever experienced this? Are there any tips you could give me? Thanks :D