As was previously said, weed does have negative effects. Mainly involving the brains functioning ability. I know its hard to appreciate effects of things when they take years to become apparent, but remember once it happens its impossible to cure. Also, if your parents dont agree with it, then for me that means you stop. not just do it behind their back, thats disrespectful. just stop, its not worth risking a relationship with your parents over, and in fact they'd think more of you for kicking the stuff.
Also, remember what you've said. teenagers are meant to make MISTAKES, but you learn from them. I completely agree, not just teenagers, everyone makes mistakes. the point is, you learn from it, and in this case that means you stop using weed. otherwise you havent learnt anything at all.
In case you cant tell im very anti-weed, one of my best childhood friends was alienated from everyone because of that stupid drug. It takes a stronger person to say, my friends and family are more important than a few minute high. its a waste of money and never leads to anything good. Just stop now before you do any serious harm, to your friends or to yourself.
i expect groans for that above comment, i know a lot of you guys on this site worship weed..... sad fact indeed....