Assalaamu Alaykum,
From what I understand, among the conditions for Zakah to be due is that you need to:
- Possess the minimum threshold (nisaab)
- Possess this amount for a complete lunar year
So I am unsure about your case because you said you spent most of the money before the year was completed. I don't know whether the money went below the nisaab - do you know roughly how much the nisaab is in dollars? I think for pounds it's around £600-700, Allaahu A'lam.
Btw, your question reminded me of a new (free) study programme available online. It can be taken at your own pace, and one of the topics already covered is Zakah. So if you have time, perhaps it would be worth going through the sessions because this is a topic important for all of us to understand. Maybe you will find a better explanation and answer there Insha'Allaah.
http://www.islam21c.com/index.php?op...ial&Itemid=108
http://www.islam21c.com/index.php?op...aad&Itemid=142