Your situation sounds perfect to do medically fragile care! It doesn't have to be children who are terminal, just maybe chronic stuff. I have cared for children who are diabetic, have shaken baby syndrome, prematurity & effects from it, also there have been children who had mild to severe CP and there were several babies who were otherwise healthy, but were on an apnea monitor for various reasons.
Since you are mom to 2 little ones, you obviously wouldn't want to do the terminal ones, but if you are content to be a little more "tied down", there's no reason you couldn't foster medically fragile children. Your state, I'm sure, would be thrilled to have an RN providing care to these children! You have the qualifications and the heart...when the time is right for your family, it sounds like you'd be a natural!
God bless. I'll pray for God to give you some guidance. But, if He's given you the ability and the desire, maybe that IS the guidanace???
If you have any other questions, feel free to pm me.