How did you move your bishop if its check?
Rg7+ Kh8 Rxg6+ Rf6 Bxf6# is more forcing but chessbee's line is also correct
1.gxf4 gxh5?? 2.Rg7+ Kh8 3.Rg6 (or 5 or 4 or 3) #.
But 1. ...gxh5?? is a mistake.
Black should play 1. ...Rf7 Bg4 but White is winning easily.
I don't understand what you mean when you said "I retreated my Bishop to f3."
You are in check ...
I think perhaps the position was set up incorrectly. I believe the King was on a different square.
Thanks for all your help guys. You are correct, I set up the king on the wrong square. I'm pretty much a rookie so I didn't know to write down my moves as I was playing the game, so I had to reconstruct this from memory a couple hours later. Next time you can bet I'll have my notepad handy!