What to do.......

I am having a really hard time deciding if we should have a 4th kid or not, and if so, when. See, Justin really wants to start trying again, but I am just not sure. Part of me really wants 1 more & another part of me is wondering if someone is trying to tell me something. Should I stop now, I have 3 beautiful, healthy kids. Some people never even get 1 healthy baby. The results from the "tissue" testing said we have no problems, just "bad luck". Well, bad luck stinks! What should we do??????