You dont need to buy ketostix at all. Being in ketosis is just the thing that stops you feeling hungry and gives you energy, people seem to think it's what burns fat but this is not true.
Most people hit ketosis by day 7.
When you do your AAM (add a meal week) you need to have high protein and low carbs.
Things like chicken, eggs, quorn, green salad.
There are lots of recipes in the recipe section on here.
You'll be fine, as long as you dont use your AAM to stuff your face then you wont gain weight.