Shooting basketball help?

I play basketball in a competitive league now. I have a complete game i'm a good defender,passer, and ok scorer. My midrange shots are pretty consistent around the freethrow line. My coaches, teamates, and other teams i've played agaisnt haven't really mocked my shot because its mostly swishes in the net, or looks like a swish everytime i shoot. One day i played agaisnt these random teens at the park and they mocked my jumpshot. I am 13 and my shot is similar to Magic Johnson. My guide hand leaves the ball once i jump up and it looks like i shoot with one hand. Now it's hard to change my jumpshot after mastering the midrange almost and shooting the same way for years. Please help me.