i've been thru that too, and is not nice, but you can try putting more attention on what you do, be more ordered, smart and clean specially when its about da' stuff, also, if opportunity arises and you have a discussion with your parents, and they bring false facts about weed, it doesn't hurts to enlight'em a bit with proven facts, so they dont feel it as being that bad, or that you do it without thinking about consequences, but that may never change anyway, parents worry about their offspring, they like to think that your friends are the ones to blame, not their beloved son.