Angelfish - reading your post was like reading my mind. My DD #2 is only 5 months old and i already yearning to be pregnant again. Like you i think what i can give my two girls in the future, and what it would be like if a third came along - would i be able to give them as much.
I have a 'nagging' feeling that i am not 'done' with having children. Its an incredible urge and i honestly think this urge (gut insticnt???) will overide the need to buy a bigger car, a bigger house, more sleepless nights etc.
I just have one slight prob - at the moment DH is in the 'we'll see' mode. So ive got a bit of work to do......