The official NHS dietary advice for everyone, diabetics included, is still the "Eatwell Plate" which recommends basing all meals around starchy carbohydrates. It also says no sugar (OK) and little fat (not OK, IMO). I have had success (five years on now) on a very low carb "keto" diet of around 20-25g carb/day. This has meant no bread, pasta, rice, cereals, potatoes, sugar, fruit etc. all of which are high in carb and also usually eaten in some quantities.
My T2 course was notable for the friction between the diabetic nurse who was pushing carbs to us via the eatwell plate, and the dietitian, who was telling us that carbs were totally unnecessary and a low-carb diet was preferable for diabetics, plus good natural fats were not a problem. There was, not surprisingly, a lot of confusion.
You are therefore far from being alone. Fortunately there is a much bigger awareness these days of the problems carbs and processed food in general are causing, and a wider range of sources of advice who are happy to contradict the official line on diet.
On home testing - are you using a fingerprick glucometer? I think these are essential if you want to understand more about how various foods affect your blood glucose. You can pay for additional HbA1c tests over and above the ones the NHS carry out, but I have never seen the need for this. The NHS won't take any notice of them anyway and they are not much help in adjusting and managing your diet.
I've never used an app, so can't really recommend one from personal experience. There are several around.
Best of luck. This forum was an essential resource for me in my early days. You'll see that there's never only one answer to a question. Thing is to find what works for you.