Sooz, don't start fretting with keto sticks, they are very misleading! First of all if you have stuck 100 % to the diet you WILL be in ketosis. Ketones are excreted by your body when it breaks fat down on this diet, however because of the amount of fluid you drink on this diet your wee is very diluted and therefore may not give an accurate representation of that fact. The most accurate wee to dip is the first of the day when your wee is at its most concentrated. But don't be hung up with it. ! stone in 2 weeks is fabulous, you have already smashed 1 months predicted loss, and if you were to lose 3.5lbs each week you would lose a stone in a month.
When I went to LL we had to wee on a stick and very often we showed no colour change in the stix. One lady got very upset and said she must never have been in ketosis while doing the diet so it mustn't be working; then the counsellor asked how much weight she had lost and it was around 8 stones in something like 6 months. Counsellor replied I really do no think you need to worry about not being in ketosis.
My advice is throw the sticks away! if you are not hungry, losing weight, cold and got breath that is horrible, you are in ketosis and don't need to pee on a stick to check. Chin up girl you are doing great xxx