I get you OP. You are clearly investing a lot in a diet which isn't paying off.
I've tried 5-2 and low carb, and not for me. I got so constipated on low carb and very light headed. I need balanced food to function (mostly because of my job). I've started this diet plan called showme.fit, it has good recipes (not all recipes are great, but I've selected the ones I like) and they are quite filling. I don't count calories, or feel like I'm starving and I've lost 4 pounds the first week. It's all very healthy food, wholegrain, lots of vegetables, some carbs, and I feel pretty good about it. Snacking is just fruit and veg. There are also exercise videos but I don't do them, I run 3 times a week. It's a paid website but quite cheap.
I've never 'paid' for a diet before (although I bought books) so it's hard for me to compare. Also I only need to go down about ten pounds, which is what I put on during lockdown so I don't know how the diet performs longer term. But it does feel quite healthy to me with healthy fibres and balanced meals.
Typically, it's plain or greek yogurt with fruit for breakfast with a bit of honey, or something egg based with brown bread, or porridge with fruit, or home-made flapjack. Lunch is salad or soup, or brown pitta wrap, with home-made humous and salad. Dinner has loads of different recipes, things like halloumi burger in brown bap, sweet potato chips, pasta dishes with loads of veg, fish etc. Also switching to low sugar oat milk instead of cow's milk.
Maybe it's because I can't quite seem to get the hang of calorie counting (it's very time consuming) but I just prefer