>>687320-12C really isn't that bad, OP. Your gear seems adequate. Bring a small fleece blanket or -liner, and perhaps an extra ("thick(ish)"?) sleeping mat.
Most importantly, bring extra fuel for you stove. If too cold, you can always make coffee, tea, hot chocolate or whatever, or just run the stove for fifteen minutes inside your tent to get the temp up.
Moreover, if bringing a canteen/nalgene, fill boiling water in it, wrap it in a couple of socks, and use it as a heating element between your legs. Also, as bonus, liquid water when waking in morning.
