If they were very dark, you probably were in need of fluids. What time of day affects colouring. For example, your first wee of the day will be darker.
The simple thing to remember is this, if you are on the chart you are in ketosis. I know it is easier to say it than do it, but try not to get too bothered about the sticks.
If you dont feel hungry, the chances are you are in and it is working. If for some reason you start to feel starving, do a stick test. If you are out, think back about anything you might have done to knock you out.