Gaining Muscle?

Ok so today i feel a bit discouraged I have been on my workout plan for a month now and in the first two weeks i seem to loose alot of weight. The problem was I had some cheap *kitten* scales and when i stepped on them they said something different every time like it would say 71.2 kgs then 5 mins later say something wildly different. So two weeks ago I bought some weight watchers scales pricey ones and it said the same thing every time so i knew it was working. So then it said I weighed 68.8 kgs now its saying 71.6 kgs two weeks later.

So yes I have been calculating nd weighing everything i eat accurately for fat loss i would be at 1800 cals a day for extreme fat loss 1300 cals a day for my height weight age etc my average calories per day is 1431 I am in a deficit of 3500-4031 cals per week.

I think I may be gaining muscle my triceps no longer jiggle and i have muscle definition in my back I am weight training 3 times a week and cardio 3 times a week been very consistent also my quads are much harder I can actually see the muscle now and the skin on my thighs are much tighter too and my cellulite has dramatically reduced but im not loosing weight on the scales?

I checked my waist and my thigh and hip measurement its the same as it was 2 weeks ago the thing is i look taller because my sore looks smaller how can i look smaller but not be smaller and actually be heavier than i was its just nuts.

So please dont tell me to up my calories or to reduce them im almost 6 ft i know exactly what i need and I am following a plan I am wanting comments form people with experience in this issue who have done weight training and have gained muscle weight etc I want encouragement and facts not alot of confusion please.

On a side note i think i have had a bit too much salt so I am aware it may also been fluid retention so on that note does anyone have any tips on what to take to get out water weight?

Also i live in QLD Australia its bloody hot here and when i workout im completely soaking in sweat so i have been eating natural sea salt crisps like 3 times a week as MFP was saying my salt intake was very low and i was feeling dizzy and light headed so perhaps i had too much salt in the end i dunno im tired and over it today would like some good advice and encouragement really.