One thing I'm getting is that you are hypersensitive/allergic. It seems like the slightest thing can throw you off balance like the wrong brand of salt or the wrong vegetable. This is a vata trait.
Bloating is also a vata trait. Liking summer heat would be a vata or kapha trait.
parasite infestation would be a vata imbalance as well if it's centered in the colon.
Needing and feeling good with salt is also a vata trait.
A strong imbalance in vata can propagate up as it were and create what it seems are kapha or pitta imbalances, but at the root it's really excess vata (air).
Anxiety attacks/nervous debility are also a vata related problem.
Vatas will gravitate toward moist and oily foods. Adrenal burnout syndrome is a vata disorder. Kaphas can diet/fast and exercise their way out if things whereas vata once depleted cannot do this.
I'm still trying to find out what is the best way for you to go, and it's not so easy - which again makes me think vata for you as you seem sort of like a riddle.
Highly unlikely you're rid of parasites despite your previous cleansing.
My standard step 1 for parasites is eat a lot of fresh papaya and drink fresh made sweet pineapple juice - if you can afford it. It won't cure you if you have a deep problem but both are really really good, and you're getting enzymes, potassium and easy calories in the mix that cut through bloating.
I think you can rule out pitta imbalance as primary since you like heat and spicy food and salt. Pitta would not like any of these things.
When you say you like spicy does that mean hot hot peppers or does it mean savory spices. It sounds like a mundane question but it can help narrow down your dosha.
I'm still unclear if you have an illness per se besides hypothyroid or do you just want to lose weight?
Were you ever on thyroid hormone? You might want to consider going on a natural thyroid medication - it's just gorund up animal thyroid and supposedly standardized for thyroxin content.
You don't need a doctor to get the hair tests, you can order them from mail or net via websites.
I didn't mean was your constipation long term I meant the current illness or whatever you're calling it.
Do you have dryness, brittle hair or nails?
Kapha does well with occasional fasting. If you are fasting because you are too bloated to eat, that's not really fasting, that's something else, and it's likely an extreme vata problem again. Getting the dosha accurate is one of the most difficult things.
List your top 5-6 symptoms in order of severity. It sounds like thyroid and parasites to me at this point, and you need to get your digestion in better order or learn a little more so that you aren't so reactive to the slightest things.
Have you tried triphala? It can help a lot during parasite die-off.
Thyroid needs tyrosine - from either proteins or supplements, iodine, selenium, fuel, proper functioning adrenal glands. Hair test will help to shed some light on some of the thyroid killing metals, electrolyte ratios, mineral ratios, etc.
What is the reaction you get to those foods like soy, is it more bloating or is it more edema/swelling. Bloating has more to do with air and it points to vata, edema and water retention points to kapha. Kind of sounds like you're vata kapha to me at this point but this is still guessing.
I will point you to some subtle things you might not have been oriented to. Potatoes, though they are a starch are very vata aggravating, the same goes for salads and raw vegetables, and yeasted foods. So you might say oh I don't do well with starch or bread, but you might very well be fine with cooked rice and flat breads with no yeast.
Banana and mango would be good for vatas - heavy, moist and sweet. Raw apples would be terrible for vata and doubly so if they are not sweet. Stew them and then they transform to being excellent for vata and terrible for kapha.
Back to parasites, since you like spicy foods start having a lot more of them. They are all antiparasitic, some hit way above their weight class, but you have to just go through them one by one and mark how you feel. If you like cayenne or hot peppers these are great antiparasitics.
You need to do some leg work to find out about which things cause your body temp to go down, then you can eliminate these things and see what happens.
Soy should be fermented or well-cooked, not soy milk. I think you might want to stay on some form of Iodine like kelp or low dose Lugol's even when you're not doing the official Iodine protocol - which you might want to consider as well.
Regarding water. Pitta usually feels good drinking cool spring water. Kapha might drink a lot of water, but it can actually be a negative addiction making them more edemic. Vata, not sure, they might like it or not. Extremely depleted vata would not like water. This makes sense as you're not in a terrible state now, maybe sort of a like a B-/C+