I'm really sorry to hear what you're going through. I had a miscarriage at about 6 weeks and as soon as they did the ultrasound and detected no heartbeat they told me it was for sure. They haven't told you that yet, and I think that if they thought you had most certainly miscarried then they would have said that to you. If I were you I would just remain cautious and hope for the best.
And just a note about the head lice since you are a teacher and will most likely encounter it again. I use this comb to treat my daughter when she gets it at school and myself whenever I've gotten it from her and it works without having to use any of the chemicals and it's really easy to treat yourself. http://www.amazon.com/Terminator-Professional-Stainless-Treatment-Removes/dp/B000HIBPV8 It's on ebay cheaper than this, too.
And just a note about the head lice since you are a teacher and will most likely encounter it again. I use this comb to treat my daughter when she gets it at school and myself whenever I've gotten it from her and it works without having to use any of the chemicals and it's really easy to treat yourself. http://www.amazon.com/Terminator-Professional-Stainless-Treatment-Removes/dp/B000HIBPV8 It's on ebay cheaper than this, too.