okay, no one else has asked so I will -- are you sure that your old suit, the 7mm that you get cold wearing, is the right size? Too many people buy a suit and don't realize that it should be tight, very tight, just short of uncomfortable when out of water. I used to tell people (I used to work in a dive shop) that if they can put on a wetsuit in less than 5 minutes, it is too big!! It really should be snug, the neck seal, the wrist seals, the ankle seals should be snug enough not to be letting in water constantly. The new stretchier suits on the market are easy to take off and put on, but they also let in more water, therefore are not as warm. Keep that in mind, too. You may need to go down a size or even two to find a suit that fits correctly.
Also - it is very important to use gloves, hood, and warm booties in order to keep your whole body warm. You are losing warmth at each of those points if not covered.
I am about the same size as you - my last 2 dives trips were to Roatan and Cozumel (water temps 78-80) and I wore a 5mm suit and a 3mm hood both trips, and the DMs and other boat passengers thought it was funny... at least the first day. After the second or third day people were asking me about my hood and telling me that they wished they had brought more than a 3mm suit. In Roatan I ended up loaning one lady another one of my hoods (I brought several). She said it helped tremendously.
On my trip to Palau a couple of years ago, I wore a 3mm fullsuit and a hood... once again, DMs laughed, but it helped keep me warm doing 4-5 dives per day! Water was 83-85 degrees but over the week on a liveaboard, your core temp does drop.
robin
