Thanks for the comments. In the game I was thinking about the line -qwwqww- mentioned, but I didn't think it was much better than the line I chose. But indeed it gives me a small advantage in tempo.

I think you are right too Bigfundu, instead of playing Rc4 I (should?!) could have played Ne4, I guess. This weakens my pawnstructure if white wants to exchange pieces, but on the other hand trades the knight for a bishop, whith a small advantage in this position?

I think the manner in which you traded queens gave white a bit of an advantage going into the endgame. You could have gained some tempo with 16.. Qa5+ 17. Qc3 Qxc3 18. Rxc3 b5 threatening b4.

I guess your light colored bishop stayed locked behind the pawns for quite a long time and the knight wasn't very active either. That could have been one of the reasons, although I would certainly need to be more imaginative than you had been to use them fully.

I was black by the way