No sweetie, it is a sad thing. I also have two children (and two totally uncomplicated pregnancies) and lost my third. We are TTC now and I still feel like something is missing even though I have two wonderful babies.
YOu absolutely have the right to be upset. Sometimes it helps me just to hold my babies and cry when I need to. They are too young to understand what is happening, if they were a little older I probably wouldn't let them see me get upset as much.