well you both played the opening very well for such low ratings... you played well but your opponent made some serious blunders which you made him/her pay for
Analysis Please
This is nonsense about the opening being played well.
5. a3 is a mistake. Nc3 to prevent black from plaing 5. ... d5 is almost necessary there. But 5. ... a5 just lets white get away with the mistake. 5. ... d5 is much better. I get that you're concerned white will play b4, but playing a5 is a very passive way to deal with this, the move doesn't do anything else positive for your position.
And then white goes and trades his good bishop for black's knight on f6. 6. Bg5 h6 7. Bxf6 Qxf6. What is the point of that? This hands over the initiative to black in my opinion. Since white's central pawns are on light squares, white's dark squared bishop will have more mobility than the light squared bishop, he shouldn't just trade it for no reason.
8. ... d6. This move allows 9. Nd5 which forces the queen back to d8 to defend the fork, this reclaims a small initiative and with a lead in development white could start to open things up with 10. c3 intending to play d4 at the right moment.
10. Nb5? 10. Nd5 was way better. It carries the same threat againt c7 but forces black to defend with 10. ... Qd8 relieving the pressure on the f3 knight.
Any analysis would be appreciated.