You can't tell from the ketostix. You tell by losing weight, or at least inches. That's why ketostix, though fun, aren't the be all and end all. If you're burning up all the ketones you're making, the ketostix don't show at all, though you're in ketosis.
If you're eating very low carbs, your body will be burning fat - what other options does it have?

If you can manage it, stop peeing on sticks, jump on the scales once a week (OK, I still jump on mine every day!) and measure once a week.
Good luck, Jay