Sorry to be a wet blanket, queridalady, but your weight-loss programme may back-fire on you.
For a start, not eating fat is a very, very bad thing. It is not healthy. Your body needs fat. It needs cholesterol. Without cholesterol your body is unable to make certain hormones, and without them you will get fat! Besides, eating fat does not make you fat. On the contrary, research has shown that those that eat the most fat lose the most weight. I know it is high in calories, but you need calories when you are hypo. Forget the calories in vs calories out mantra, it just doesn't work when you're hypo. You need fat, protein, fruit and veg, and certain amount of carbs. We hypos do not function like other people.
As to the exercising, all that exercising is probably what is keeping your T3 so low. Exercise uses up your T3. In someone with a normally functioning thyroid, the gland can compensate for the hormones used up. You cannot. You are using them up and leaving nothing for other bodily functions such as metabolism.
Exercising also uses up your calories, and it doesn't sound as if you're getting enough as it is. I know you're going to tell me that that's the point! lol But, as I said, when you're hypo the rules no-longer apply. You need calories for every bodily function, such as breathing, digesting, blood circulation, etc. You also need them for your conversion of T4 into T3. If you cannot do this then you are going to get more hypo and thus put on more weight.
And quite apart from all this, the weight you've put on is more than likely water-retention (that's what we hypos do! lol). We fabricate a substance Under the skin called Mucin, which holds water. No amount of dieting or exercising is going to change that.
What you need to do - and I know it's not easy - is to increase your T3, by whatever means. Then you will be able to lose weight more easily without torturing yourself.
I put on so much weight when I started levo - although I've never been thin - and even more weight when I went onto Armour! It just didn't suit me. I don't know exactly how much weight I put on over those 10/11 years because I stopped weighing myself when the scales tipped 120 kilos! It was just too depressing, and there was nothing I could do about it. Until, that is, I went onto T3 only, a couple of years ago. I just couldn't convert and the T4 made me ill - not saying that's your problem! Just telling my story. Anyway, on T3 my levels have risen - as you would expect them to - and the weight has mostly come off, about 40 kilos I'm guessing, need to lose about another 10, and I don't diet or exercise. I eat what I want, when I want it, and how much I want - although I don't have an enormous appetit - and I eat lots of fat. Because I like it and because I'm desperately trying to raise my cholesterol! Exercise is difficult for me because I've lost a lot of muscle strength whilst being horribly hypo and having low growth hormone.
So, tell me to mind my own business if you like! But I hate to hear stories of how people are struggling to lose weight when it's usually the doctors fault for keeping them hypo. Hope you get your T3 soon.