having another baby is completely personal, if you don't feel comfortable having another one, for whatever reason, then don't!
i'd love another bub, but i also get hyper-emesis, acid reflux, hormonal uproar etc, and after the crap that my body is still going through from miff's pregnancy, i probably will not have another one. these are selfish reasons, i don't like what happened to my body physically, or my mind mentally and emotionally. sometimes you have to be selfish, because if you have another one, and you're not 100% sure you wanted it in the first place, who knows if you'll resent it?
i know, i know, i'm blabbering now, and i don't even know if i'm making sense..
don't feel like you should have another baby, if you'are not positive, then either give it time to see if you change your mind, or leave it at the 3 beautiful kids you have!