I appluad your descision to wait. I have a 2yr. old son and a 6 month yorkie and it is hard. I have to be so vigilant when they are in the same room (which is 90% of the time). I'm terrified my son(35lbs) will squish baxter(3lbs).
I think you will be taking on too much with 3 babies in the house. Enjoy your family now and add a new furbaby later.