I have had GD, rampant GD that was not picked up until 28 weeks. I've seen your threads and concerns, and I understand you want a definitive diagnosis to put your mind at rest, but my own point of view is: What happens if you are diagnosed? Will you do things differently then? Why do you have to wait to do things differently? Or is it a case of hoping that medication will fix something?
I'd hope that the same thing happens with diagnosis of GD/no GD as is happening now: that you are meeting the nutritional needs of you and your baby. I'm not really seeing how an extended overnight fasting time, an apple and bits and bobs for food is doing that. Whatever a meter says.
I'm not a doctor, but I have been through GD, and then I avoided it for a subsequent pregnancy (full term, totally healthy and normal weight baby), by following the same protocol as I was given before: carb counting with specific guidelines for each meal, and that involved eating 4x a day (number four was literally just before bed, so there was definitely not an extended fasting period), plus 2 snacks. I'd never eaten that much food in my life! But they were certainly very different types of food than I'd usually eaten before.
You're growing a beautiful little one, and you want to keep them and you healthy and safe throughout this wonderful pregnancy. If you really believe you have GD, you should eat as though you do - and that involves eating properly and healthily.