The -3 is the baby's station. Zero station is when the baby's head is engaged in the pelvis at a specific level of the pelvic bones...one centimeter above that level is -1, so your baby's head is 3 centimeters above that level (not yet engaged low in the pelvis.) When the baby is descending into the birth canal, the numbers are positive (+1, +2, +3 station). But just because your baby's head is still higher up doesn't mean that birth is not imminent - some babies don't drop down low before labor starts.
I agree that the blood is a good sign - usually that means that the cervix is dilating/effacting because that process breaks some of the little blood vessels in the cervix. I had bloody show (mucus with blood) all day before I went into active labor that night with Ian.
I'd say just make sure everything is ready to go, and then try to rest as much as you can right now. Don't work yourself up thinking "this is it" until you are sure you are really in active labor, though! Is your DH coming back soon??