It does not matter what is in the beer. It only matters what the beer tastes like. They don't look at your recipe or anything like that.
Does it taste like an American Amber ale? If it does, enter it as such.
Others that it "might" taste like are ESB maybe. Or if it was low hopped possibly an irish red. Maybe an Alt, but I doubt it.
Maybe go buy a couple bottles of american amber, buy a couple ESB's (Not in clear or green bottles) and taste them alongside your amber..... which is it most similar to?
You say that you "used" some european hops...... but does it "taste" like a european beer? that is all that matters - what it tastes like.
Kegged/Serving: Citra IPA, Oatmeal Amber Ale, American Wheat, Ordinary Bitter, Double IPA
Bottled: Barley Wine, Sour Belgian Golden on Cherries, Sour Cherry Stout
Primary: Heady Topper Clone, Double Citra IPA, Munich Helles
Secondary/Lagering: Schwarzbier, Oktoberfest, Bourbon Barrel Porter
Future Brews: Bo-Pilsner, Porter, APA, American Brown, Oatmeal Stout, Schwarzbier #2, British Dark Mild, More...... More....... Beer.......