What's the best move ?

In this game, I had just found some space for my Queen after many stressful moves of being close to trapped.

I'd expected White to exchange Queens on c2, but instead he played Qa3.

The exchange of pieces proposed seemed fine for me, and finally resolved the Queen issue.

So, what to play now in response to Qa3?

I chose, not necessarily a ' wrong' move, but certainly not the best.

And you ?

Black to Play