Jesus christ, I wish it would be compulsory to click on 'See all' (OP's posts) before commenting. Walnuts seem to be the new 'cancel the cheque'..
Anyway, OP, I'd suggest you track your intake for at least a week, weight everything you consume and log into the MyFitnessPal. EVERYTHING. And be mindful of cooking oils, sauces and what you drink too - sugar/milk in your coffee/teas, fizzy drinks, milk, etc.
Years ago after a pregnancy (plus other related stuff) and substantial weight gain I've lost more than 7 stone by religiously tracking my cals. RELIGIOUSLY. Weighted everything, including cucumber slices and lettuce. Went on a very low cal diet, lost all the weight. Did it very quickly, as it was the only time in my life I was overweight and I just couldn't be faffing with 'slow and steady' bullshit - wanted it off. That was 12 years ago, kept it off.
Back to the tracking, my mum had the same problem as you. Ate nothing - weight didn't budge. Until I started supervising her and helping her with weighting, logging and tracking things. That 'nothing' turned out to be a mountainous spoon of mayo here, couple of spoons of oil there, some ketchup, a sugary cappuccino with a colleague, a biscuit at work 'because colleague offered with coffee', an ice cream as 'it's a hot day', an apple and a banana 'because it's healthy' (yea, and calorific), glass of fizz, because she's thirsty, glass of wine, because why the hell not, it's just one glass and so on (not all those in one day, obv) ON TOP of her normal day's intake.
She lost the weight and is healthy size now. After being truly mindful.
Obviously, it might not apply to you, as you might be already tracking your intake. If so - then it's simply too high and needs lowered. And don't listen to that 'starvation mode' bullshit, I'd be dead if that'd be true. My diet was 600-800 cals a day for a good few months until I lost the weight, no 'starvation mode' interfered.