Why would anyone trying to lose weight eat peanut butter is beyond me. Then ultra-processed food (UPF) for lunch and snack is never going to help you, and that in addition to the corn thins and flapjack, includes Activia, probably your toast and if your carrot sticks are shop bought and not peeled and cut at home, they will have gone through a chlorine bath and citric acid wash. Add to it, the Maltesers, even if only 3, and well, it is not surprising you aren't losing anything and slowly putting on.
Cut the UPF and start eating whole food.
For breakfast switch to a couple of tablespoons of rolled oats with a couple of tablespoons of flaxseeds. or Fresh berries and greek yoghurt, or a soft boiled egg. Even better, alternate.
For lunch have a small chicken breast, cook it at home and slice it into fingers to eat cold or heated with green beans and for dinner have a tiny bit of rice but brown, red or black, and a big mixed salad with at least 6 different vegetables and a piece of oven baked fish.
Tea is fine as long as there is no sugar, and stop snacking. If you absolutely MUST (it appears brits can't survive without snacking everyday, not a single French woman I know snacks ) , have vegetables. Baby Roma tomatoes, sliced red pepper, or fresh blueberries if you need sweetness.
Focus on fresh food, whole food, nothing that goes through an industrial process that can harm the gut microbiome, high in fibre, high quality and variety of vegetables. More than something very saucy like a chili, make a massive tray of oven roasted vegetables, aubergines, courgettes, pumpkin, carrot, leek, .. Ditch jars of sauces, tins of coconut milk if you are using them,
To answer your question about what to do: stop going through restrictive patterns of odd fasting, or macronutrient suppression . Do a pantry and fridge makeover. Eat the foods available when your great-grandmother was alive. Fresh. Real. Nutritious and good for overall health. You want to go fancy, have quinoa, tofu , both have existed for thousands of years.