Gin Rummy question

My boyfriend and I played Gin Rummy again today, and we had a big disagreement.  Towards the end of the game, I realized I had eleven cards in my hand. I told him I was going to discard two cards after I drew next.  He said, "you can't do that."  But then, at the end of the game, I discarded two cards after I drew, and I had Gin.  He would not let me have Gin and we had to agree that that game had never been played.  Does anyone know what to do if someone ends up with eleven cards somewhere in the middle of a game?