Congratulations on braving the cold water! Our diving really does have a lot of rewards, but you work for them.
I do hope you are using a 7mm Farmer John setup, so you have 14 mm on your core? A simple 7mm suit really is not enough for around here.
A few tips for staying warmer: One, don't get cold BEFORE you dive. Wear a hat in this kind of weather, and a heavy coat, right up until you change into your neoprene. Two, get out of the neoprene as much as possible between dives. You'd think the stuff insulates, but having that wet material against you really doesn't. Three, carry hot water to put into your suit as soon as you redon it (or even before the first dive) so that you won't have that initial "flush" of icewater as you enter. Four, if you are intending upon two dives, don't prolong the first one until you are really cold. Going back into the water with what I call a "thermal deficit" is a recipe for a very short second dive. Remember that you are not really warm until you sweat; just because you've gotten the feeling back in your hands and feet doesn't mean you are really rewarmed!
Anyway, have fun with the rest of your diving here!