Should we have another kid?

Not a decision to be taken lightly.
My wife and I have two beautiful children, that much is obvious if you have seen my pictures of them. When we first met, we both had known our entire lives that we wanted kids, and as it turns out, we both had always wanted three kids. After we had our son in May of 2008 we had a conversation about having more kids, and we came to the conclusion that it wasn't a good idea for us to have any more. I was of the opinion that I have both a son and a daughter, and I'm not sure I could have enough love to go around for a third kid. Now, of course if we had one more, I'd find the love and that child would be just as loved as the first two. Plus, we are not in a position financially to have another kid. My wife and I both feel it would be irresponsible to have another kid. BUT...
Second thoughts!
Lately we have been having conversations about the possibility of adding to our family. My first thought, is HELL NO! I have said for a while now that if our son had been first born, he would have been an only child. He is that much of a handful, and that's saying it mildly. I'm not sure I could handle him as a middle child. My sister is a middle child, and holy crap she has caused so much drama in our family. I know I couldn't handle this little Tasmanian Devil causing any more drama than he already does. But, my wife is really having second thoughts. She has mentioned that it makes her sad to think that she will never be pregnant again, or have a little baby to care for. I told her "Heck you didn't have a LITTLE baby with Denny." He was 11lbs. 8oz when he was born, so he has never been "little" by any means. I'm not sure if the proverbial "biological clock" is ticking for her, but if I had my way I'd take a baseball bat to that damn clock! 
Seriously though, if she were to come to me and tell me that she really wanted another baby: I'd do it for her. I know I said it would probably be irresponsible to have a third child, and that I'm not sure I had enough love to go around. I promise that I'd make it work though. I would do that for my wife. I'd have to find a way to support my son so that he doesn't live the middle child syndrome. But, I know we could make it work. I'm just not sure I want to.
What are the thoughts of you readers on this subject? How did you decide that you were done having kids, or have you not decided yet? Am I an idiot for thinking I don't have enough love to go around? Feedback please. Oh, and I've included this link for anyone thinking about becoming first time parents. I'm not saying not to become parents, just know that something like this is going to happen and you have to know how to deal with it. http://www.youtube.com/watch?v=xWkZ_StRjU0 
If anyone does know how to deal with this type of behavior please drop me a line because you've just solved one of my biggest questions of parenthood.

I also had to include this picture. My little girl was insistent that if she colored it, I had to put it in my blog. So here it is. She sings, she dances, she is artistic. I'm not sure she's really mine! NO, I'm kidding, but she definitely gets that side of her from her mother. She didn't stay in the lines though, and I have never stayed in the lines, so maybe she does get it from me!  
Thanks and have a great night.