35 RxN works, because of Nh5 check! winning big material. just take more time. nice game, though.
Here is the reason why you don't resign against lower rated people

@OP: Nice try! The Queen and Knight are a great attacking pair; they work together extremely well, because the Knight fills in some of the squares that the Queen can't quite reach. Just keep practicing with them.
Once you were left with the Queen and Knight against only White's King, one example to win would be: on your 47th move, instead of playing 47. ... h3, try 47. ... Ng4+, 48. Kf1 Qe3, 49. Kg2 h3+, 50. Kf1 Qf2#. Alternately, if White plays 50. Kh1, then you can play 50. ... Qe1#.
Also, I thought you could develop your pieces better. Your army wasn't really fully developed until late in the game. For example, you didn't even move your King's Knight until the 24th move of the game, which also left your King's Rook boxed in the corner and away from the action. Even once your Knight finally moved, you didn't really seem to use your minor pieces much. I thought you relied too heavily on your Queen. Because of the way the computer played, your Queen was able to do a great deal of damage, but ordinarily, a lone Queen can't get much accomplished at all. On move 24, your Bishop and Knight were ready and poised to get into the game, but they weren't actually participating in the attack. So try to concentrate on coordinating your pieces better, which will, in turn, help you play the Q+N endgame the next time.
Good luck!

OK Here is another one. Just to redeem myself. But the point of this is really just to show that its probably good to stick it out and try to get a stalemate sometimes.

And you played 51... Kxf6? lol Oops! Admittedly though, that is rather a nice stalemate (as these things go)...
I am ashamed. I was a Queen and a Knight ahead and STALEMATE!! Why can't this be Chinese Chess where Stalemate is a win rather than a draw.