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: Porter, Helles, British Bitter, Dark Mild, Oatmeal Amber, APA
Bottled: Barley Wine, Bourbon Barrel Porter, Strong Scotch Ale, Sour Belgian Golden on Cherries
Primary: IPA, British Bitter, American Wheat, Dortmunder, German Pils
Secondary: Sour Cherry Stout, German Pils, Dortmunder
Future Brews: Dark Mild, British Bitter, Oatmeal Amber, American Brown, American wheat, American Pale Ale