You're correct, the U.S. is not a democracy, according to the objective political definition of a democracy.

We are a federal republic, I believe is the objective political term that mot closely matches U.S. political system. This is not necessarily a knock on the U.S. polticial system however, as there are no real democracies, and to be honest historically there were very few true "democracies," the majority of such example being Italian or Grecian city-states during the early or middle Medieval period.

Those sorts of systems don't work when power scales to a national level (i.e. 320 million citizens, or even on a smaller scale like England or France). Even in the very early post-colonial period, the Articles of Confederation granted the federal government such limited powers that they were unable to realistically provide such basic government services as "passing laws" or "stopping invasion." The Articles were tossed in favor of the current Constitutional model, and since then the government has slowly consolidated power more and more under an increasingly-powerful centrist government.

Though again, this isn't necessarily some sign of the impending American apocalypse. Majority elections still determine all members of the U.S. Congress, and almost always president. The electoral college is a bit of a clusterfuck of a compromise for the latter, though it's only failed once, in 2008, the reasoning being that tallying physical votes in one district in Florida would take months, so the U.S. Supreme Court voted in favor of Bush, because you can't NOT have a President for four months in the current political landscape.

Though, again, this is more having to do with modernization and demands of an ever-growing international economy. The more money corporations and private individuals and states have, the more government (in general) tends to consolidate its power structure to maintain some level of autonomy. If we lived in a true democracy, a company like Apple could probably just hire a bunch of Chinese mercenaries and overthrow the U.S. government, which wouldn't work well for anyone.