Mine is a 3200-xmp kit as well, ddr4 can usually go way higher if you loosen timings (some can even do it without loosening). Aim for ocing this for getting your IF at max :)
it's not wrong at all, you run at dual channel, so 1600x2 = 3200mhz, when I say you should aim to 1800 I mean DDR4-3600, so that your infinity fabric will clock at 1800 too
you should definately get your ram to 1800mhz, I can get same score as you on my trashy 3600 non-x, I'm assuming that it's cause I'm running my ddr4 3200 kit OCed to 3600