i have been vegetarian for about 8 years, stopped eating eggs soon after that and then slowly fazed out dairy. i've only been eating raw for about a month now. i'd tried it once before, but got a bit bored (mostly because i wasn't been very creative nor did i own any raw recipe books, which i do now.)
i think that is a problem with some people turning vegan or vegetarian and not knowing how to cook vegan food or are not mindful of what they need, which is perhaps easier with eating an omnivore diet because its common. i mean i know a few new vegetarians who will eat lots of toast and not much else, but i don't think there is too many reasons why one cannot live healthily and happy as a vegan, i know lots of people who do.
i never had too much trouble getting what i needed, although i used to feel a bit fatigued leading up to my period, that said my last period i didn't even notice it coming! early on i used to think about what i was eating a lot and ensure i ate what i needed to but i don't think too much about it anymore.
i eat a variety of fruit and veg (organic, packed with vitamins and minerals), i have lots of sprouts too, which i made bread from, by blending them with some spice and veg and dehydrating it, or else put them in salads or raw soup! sprouts are great because they are a living food, with lots of energy and you can sprout most grains and get a variety of what you need. i used to eat quite a lot of soy; tofu, milk, tempeh, which are high in protein... but don't now i'm eating raw.
lots of nuts and seeds have lots of protein; pepita, sunflower, brazil nuts, almonds and hazel nuts.
i think with hypothyroid, you should avoid soy products, but take in lots of iodine, i think what can be problematic with iodine is that the soil quality most veg is grown in isn't great and is low in iodine, so eat organic. you also can get it in seaweeds, i like to make a juice and put kelp or spirilina powder in it. or else i put some dried nori in salads (which is delicious!)