How long does it take for permanent teeth to fully grow in?

i lost a baby tooth a few months ago (woo hoo yea im 16 with a baby tooth! ugh) anyway my permanent tooth started growing in about 2 months ago, and it still is not fully grown in. it makes me really self conscious. someone please tell me it can take longer than two months for a tooth to fully grow in.if it takes less time then im probably stuck with this (what i would call ) GAP for the rest of my life... well until i lose all my teeth and have to get dentures... YAY WHEN IM LIKE 80 ILL FINALLY HAVE PERFECT TEETH! :p