Weed can be an excellent remedy for a number of social disfunction, including anxiety. While anxiety pills will most certainly contribute to a person's depression, weed will not make you depressed.
It can slow you down, though, and maybe that's not so good for you right now... Just guessing.

Weed will not make you want to do other (illegal) drugs. What makes people try different drugs is mainly curiosity; nobody's gonna hold a gun to your head and say, "take this LSD" or "snort this NOW."

If I had a kid, I'd probably do what your mom did - since it's not legal, I'd rather have my kid smoke it at home with me (yes, I use the herb too) than leave him/her to be harassed by the police or something.

Harm reduction, though, is never a bad concept. If you can, say, smoke only on weekends or something, it would probably be best for ya. You're still growing up. :-)

Maybe you'd like to ask your counselors about Harm Reduction? Or try www.harmreduction.org