Well if I remember right at 15 I was about as tall as I was going to get. Maybe an inch or to left. The only real growing I have done is width wise.
But I would think unless you have a major growth spurt you are going to be able to shoot the lenght of gun you are shooting now.
Now for sporting guns, I like the Beretta 391 sporting, the Browning gold sporting clays, and I really like the Winchester Super X2 Signature red sporting below. They have a walnut stock one that is a bit cheaper.