I work with several teens, including 14 year olds, and it's fine. You are not too young to lift weights. The only caveat I would add is that you need to go through a conditioning phase before "heavy lifting" or you will potentially get injured or compromise results. (That's regardless of age).
In terms of stunting growth,..how? When you
strength train, the muscles create a pull force against the bones, and that actually increases
bone density, thereby strengthening the bones. So I'm not sure I follow that line. I think (JMO) that it may have been something parents said to their kids out of being either overly cautious or overly concerned,....perhaps combined with teens lifting irresponsibly.
But yes, you can lift weights.
PS: Please for the sake of all that is holy, do not just work your pecs. Why would you possibly want to neglect the rest of your body? And trust me, a lady isn't going to drool over nice pecs and scrawny legs and arms. If you're going to take your physique seriously, think symetry along with safety.