OP - I've lost three stone in the past year on an 'eat less move more' principle diet. With an underactive thyroid, one of the traditional 'boohoo I can't lose weight no matter what I do' excuses. I'm afraid the bottom line really is that some people can eat more 'nice' things without putting on weight, whilst others have to accept that their bodies are configured in a much crapper way which means they really have to be stringent about what they put in vs their output.
In my case I've just adapted to diligently measuring how my body responds to what I put in. My basic philosophy is that if something's not 'natural', it's probably going to have more of an impact on my weight. I do weigh everyday - which I know plenty would not advocate - but for me personally, keeping a track of weight creeping up is the best kickstarter for thinking about what might have contributed to that and then scaling back for a couple of days to restore the balance.
That said, in all that time I've not given a second thought to factors such as what are 'sins', and what's protein vs particularly what's 'carbs'; God it makes my teeth nash the way the word carbohydrate has been turned into that 'buzzphrase' by the weight-loss industry. My secret was (is!) realising - accepting, I think that's the 'keyword' if there is one - that I was just eating too much, and too large a proportion of that being 'treats', no matter how much I convinced myself my diet was basically healthy. I still love fish & chips, pizza, alcohol & co - as much as I ever did - just without any such frequency as I'd convinced myself was 'alright' and that there must have been some other reason I was podgy whilst munching on otherwise nutritional foodstuffs most of the time.
But within that there is good 'ready meal' stuff out there that helps to ensure you're getting adequate calories and nutrition. Innocent Veg pots are good for work lunches, as are Covent Garden soups - I tend to stock up on them from the 'gone off' aisle in Sainsburys, which is my first stop every time I pop in

Food Doctor bulgar wheat/lentil pots are also great - you can add so much low-cal chopped stuff to jazz them up like celery, fennel etc - they're like, sorry to be snobby, 'upper class' pot noodles. Sainsbury's also have their own 'My Goodness' ready meal range a lot of which sits agreeably within the 300-something calorie bracket.
All this talk of food, but I do make sure I move more too. There's a conveniently mean hill a couple of minutes' walk away from the office, which I've got into the habit of doing at least once every lunchtime. Then there's also walking to town to get ingredients for my weekend treat 'from scratch' cooking of curries, risottos etc instead of going in the car. Two other things have worked for me - sorry to be graphic, but pooing is very important - and prune juice really does do the trick, I honestly don't know why more people aren't sold on that. In my case also, but I realise this isn't for everyone - adding chillies to stuff (seeds intact) does seem to have a positive effect metabolically.