Good job on the snacking front.
I'd wager if you entered onto a nutrition site your intake you would find that your macros will be skewed in favour of hidden carbs rather than satisfying proteins or fibre. Unfortunately whilst the calorie count is certain, the emulsifiers etc in ready meals could be playing havoc with your system and your body might be hanging onto them (for want of a better phrase!)
Without sounding patronising (I don't mean to at all!) Could you try:
Bacon/Egg muffins - these are dead easy, you could make a batch keep in the fridge and eat over 2/3 days. Simply get a deep muffin tin that holds 12 muffins and then spray one-cal or a rub of butter around the edge. Then wrap a rasher of streaky bacon around the inside and cut another in half and place in the Bottom so it forms a 'case'. Then crack an egg into the middle, sprinkle with fresh chives/chilli flakes and bake for about 15-20mins at 180. Each is 219 calories assuming the egg is large. v low (if any carbs).
Just plain unadulterated greek yoghurt, a tablespoon of maple syrup (if you want something sweet) and make your own granola so you know what's in it? I know it's a bit faffy but you'd probably save money in the long run.
Lunch - could you prep a salad in advance and have that? Rocket/tuna/Egg/Green beans or Roasted butternut squash with Harrissa/Feta/Rocket/Pumpkin seeds are my faves.
Dinner - my go to is chicken thighs roasted in the same tray as a variety of veg and toss the whole lot in harissa seasoning,oilve oil, sea salt. I usually have cauliflower, courgette, sweet potato, fresh mini plum tomatoes and red pepper. Minimal washing up and sweet potato is lower in carbs than white potato.
On the white potato front, if you cook white potatoes then let them cool and reheat the starch bonds alter so that you actually absorb less carbs than eating them straight away.
Pistachios are great if you buy the in the shell. They take longer to eat and a large bag at Tesco is £2.65 and lasts a few days.
Personally I find lowering carb content is my go-to for losing weight and they are pretty much hidden everywhere (including natural sugars in milk for example)