@Peerless67 - I've just had a catch up on this thread, and I have to say you're really doing well.
I know most places suggest only weighing weekly, but bearing in mind your variances, and that you are learning a lot, I might be inclined to suggest that whilst on the ND that you consider a daily "step-on-step-off" routine with your scales, but an "official weigh in" on your chosen day, weekly?
I have been the same weight for well over 3 years now, but I do vary differently most days, within +/-1kg (i.e. a 2kg range). Sometimes it can be more if all the weight factors are in play at once.
Daily I do the "step-on-step-off", which is literally that, then once a week, I use the further functions of my scales to measure my %fat, %muscle, visceral fat and so on. Like doing bloods regularly, it has taught me where my natural running ranges are, so that the variances are just what they are.
I'm not suggesting for a moment you are doing anything wrong, or that my way is superior in any way, it's just a further way to familiarise yourself with your body and it's workings.
Good luck with it all.