S.N.
I think almost every woman wants a new baby when their youngest is getting to the preschool age. Most of the mom's I know did, anyway.
I think it would be wise to take some strong introspection to figure out exactly why a third baby is so important to you. If you are still convinced that you want another baby for all the right reasons, start looking at it from your husband's point of view. Another baby means you are going to be outnumbered by your kids. This is a silly thing to most of us women. But to guys, with their naturally strategic ways of thinking, this can be a daubting task, not to be taken lightly. Also, even with you working, you husband is likely to be thinking about his ability to support another baby. Also, he could be thinking about that blissful time in the future when you two will be able to once again enjoy each others company without worrying about the kids. As desperately as my own husband and I want another baby someday, we can't help but think about the fact that, in a few short years, we'll be able to go out for dinner or away for a weekend, without it taking the kind of preparation and forethought that goes into building a small city.lol
Enjoy the family you have. Look for the good points of keeping your family just as it is. I'm sure one way our the other you'll pull through.