The joys of American healthcare

Even though I've got medical insurance through my job, I still seem to end up owing loads after a doctor's visit.  The American healthcare system absolutely sucks.  It's crazy, it's confusing, and it's a mystery to me - I've got no idea how they calculate the final number I owe in the end.  It should be simple - you pay a fixed amount at the clinic for each visit, then pay up to an annual deductible for services rendered.  As soon as that deductible is reached, the insurance pays for the rest.  But it seems more complicated than that - I can't work out how I owe the amount I do, it seems like I'm paying for my clinic visit twice.  I might have to call up my insurance company and have them explain it to me, no matter how stupid and naive I might seem.  And I've got to go to the doctor's again next week.  God knows how much this visit is going to cost me.  Just so stupid.  The NHS may have it's faults, but at least it's free.