Hi, I found this site and it has amoung other stuff, a nice description of each of the categories of CM. It's certainly helped me to understand the CM stages.
https://www.gettingpregnant.co.uk/naturalfertilitymanagement.htm
Basically:
Sticky: As your period ends you'll priduce no fluid, or fluid that is dry and sticky. The vagina feels dry unless sexually stimulated and sperm cannot survive.
Wet & Creamy: As oestrogen levels increase you'll notice a wet or watery feeling and an increase in fluid which is slippery when rubbed between the fingers. May take some time to dry and feels creamy, almost like lotion. This is fertile quality, sperm can survive in it and you should BD every other day when you have it. May last several days
Egg White: At peak fertility when the egg is about to be released CM likely to reach consistency remarkarably similar to egg whites. Its slippery and can reach an amazingly long way when stretched between the fingers. Not all women get this - some do not progress beyond wet and that should not affect your ability to concieve. Others may have it for just a few hours for tp to 3 days.
Sticky: after ovulation you will return to sticky or no fluid.
If you consistently find it hard to detect the changes you may not be ovulating and should visit your GP.