How do i know when i have stoppd growing?

last year june 2010 i was 5ft1 by the beginning of 6th form i was 5ft 5 by january i was 5ft7 and in feburary I am just under 5ft8 but since feburary i havent increased in height whats going on, my dad is 6ft2 and my mom is just into 5ft5, i look exactly like my dad just without a mustach, he said he had a late growth spurt, is that what is happenin to me as i am one of the smallest in my class? nd do you think i have gt my dads genes.