Artichokes are so weird. We bought a couple of small plants from a nursery at the end of last year and planted it. By March or so we were getting artichokes left and right.
Here was one of the first ones we got:
http://yfrog.com/h2kx1mjaj
We actually let a couple of them go - we had two varieties, I think, one was definitely globe, the other was probably meant to be ornamental. I got a pic after it had blossomed. It's quite pretty!
http://yfrog.com/gybpyrej
We had a surprisingly cool spring this year (very odd for New Orleans). As soon as the heat of summer picked up, though, the plant started suffering. It started to grow some shoots, so hopefully I can divide it and replant it for next year ... if it survives.
If you've never grown them before (this was my first time) the first one is big, then the next ones are a little smaller, then each one after that is smaller. The ones on there right now are about the size of a walnut. I had read about this, but we found it to be true.
I'm not sure what climate they thrive in, and I've heard of lots of people down here having all sorts of issues, so maybe we just ended up lucky. It looks like yours is still going, though, so I wouldn't give up hope yet!