A Winning Position...?

A Winning Position...?

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Playing in my school's chess club today, I faced off against Adrian (you'll see him in my blog entry "Chessing"), with me utilizing the black pieces. After his move Nf4-d4, the game reached the current position, which I pondered long and hard after he groaned, proclaiming that he had made a mistake(he begged to take the move back, but I wanted to see what I could do first):

 

 
I played Qa5. Adrian got cocky after this (I must have missed the opportunity he saw) and made a few deliberate mistakes, because he "felt bad for me."
The game reached the following positions, chronologically placed:
 
And Adrain resigned.
Can anyone find a better move than Qa5 from the first position I gave?
Thanks for the help!