Welcome Bride12!
I was a vegetarian for years... I tried to remain vegetarian on this (wonderful) diet but indeed it is hard.
After a while I got tired of yogurt and tofu and I was very, very hungry no matter how much dairy I had.
I still remember the first time I decided to go back to meat. I bought chicken liver I did not even stand before..
I am on Dukan diet since 25th of July 2011.
I got good results and I am pleased.
You can have fish and that is great.
You should definitely give it a try.