Sorry boys, this ones for the girls. ITS ABOUT PERIODS SO READ AT YOUR OWN RISK?

okay, so i am seventeen, not sexually active, there is no chance of pregnancy and i have my period. ah duh. anyways, today when i was urinating a huge, squishy clump of blood came out. it was bigger than a golf ball, but smaller than a tennis ball. my periods are normally really watery, and they come every three months. sometimes i get the gross clumpy periods, and i know this sounds totally gross, but its almost like taking a crap, but not from the anus. i read online that if the clots are larger than a quarter than you should see a doctor, and mine are always larger than a quarter. sorry if this grosses anyone out at all. i just want to know if im healthy before i have a huge discussion with my mother about huge clumps of blood squirting out of my vag. :/