The best way to tell is an U/S, and if nothing is showing in your tubes, only in your uterus, I would count on one healthy baby. Pain
and spotting can be many things, especially an infection, pain
in this stage of pregnancy is normal because your uterus is coming above your pubic bone, and this can cause a lot of discomfort as it shifts everything else, not to mention everything is stretching right now. Good luck hun, keep us updated!!