I am hopelessly in need of some of your help :)

As another poster has already said, TS4, TS3 and rTS3 levels don't always directly correlate with TSH, and TS4, TS3, and rTS3 are really what determine your metabolic rate. This would be my prime suspect. There are many cases where TSH can be elevated significantly while TS4 and TS3 remain deficient and your TS3:rTS3 ratio remains below healthy values, as in the case of sustained very-low-carb dieting.

Ooookay, so what to do about it? I'm a little conflicted here, but it seems like there's a lot of anecdotal evidence saying that intermittent fasting can improve thyroidal function, while there is a study out there that seems to indicate that thyroid production is down-regulated during fasting. It's important to note that the study did not take into account people who take thyroid in supplemental form, and the improvements found in these folks could be more to do with the body's use and conversion of TS4 and TS3 while fasted rather than endogenous production rates. Ultimately I do not know for sure, but I would definitely try intermittent fasting out. Here are the links.

Pro fasting:
http://perfecthealthdiet.com/2010/12/intermittent-fasting-as-a-therapy-for-hypothyroidism/
http://voices.yahoo.com/how-fasting-impacts-hypothyroidism-12116831.html?cat=5
http://thyroid.about.com/u/reviews/loseweightsuccessfully/Thyroid-Diet-Weight-Loss-Programs/Intermittent-Fasting.htm
http://thefastdiet.co.uk/forums/topic/fasting-with-an-under-active-thyroid/ (See post 2)

Against fasting:
http://www.ncbi.nlm.nih.gov/pubmed/18225975

What I do is aim to get my protein in (130 g for me -- based on 0.7 g per lb body weight) and keep my carbs below 80 g. I don't worry about the percentages per se, but it ends up being 10-15% carbs, protein is 30-35% and fat is 50-60% as result.

As for how I do Primal, this is what it usually looks like for me:

It usually means a couple of eggs, sausage, piece of cheese (my version of an Egg McMuffin without the bread/biscuit) and half a grapefruit for breakfast, big old salad with protein (usually chicken, sometimes steak) with full fat dressing for lunch, then protein and veggie for dinner (steak and artichoke like last night, sometimes pork with an apple ginger chutney I make and asparagus, duck with sweet potato, etc.). I love sweet potatoes and would eat them more often if I wasn't looking to restrict carbs -- so I only eat them sometimes. I find it to be very similar to French cooking if you eliminate the bread -- great, rich sauces go great with protein and veggies. The two things I struggled with missing were my penne alla vodka and panang curry because the first is served with pasta and the second with rice. Then, I was introduced to spaghetti squash and it's an awesome sauce delivery vehicle, so I have it with both my vodka sauce and my panang curry. And I don't feel all bloated afterwards or have a major sugar crash later as I would have had with the pasta or rice (I do envy those that can eat high glycemic carbs easily!).

I'll throw in the occasional extra piece of fruit or sweet from time to time (usually, dark chocolate or something like creme brule or panna cotta). My dairy tends to be mostly butter, cream and cheese (usually for sauces or cooking veggies) and occasional whole milk (though usually as part of a recovery drink after lifting with some extra protein powder). I tend to snack on things like deviled eggs and nuts. I also tend to eat 1650-1750 calories per day, though I burn 2400-2700 on average. I'm also 183 lbs and looking to get down to somewhere around 160 or so, or I think that will be a good goal weight now.

For me, this way of eating is totally fulfilling and easily sustainable. Once you get used to it, it becomes second nature and the planning aspect isn't so bothersome. And if I want an occasional cookie or cupcake, I have it. But, I've found over time, them not to be as appealing as they used to be.