I have a very thick white clumpy discharge? Is it normal and if not what could be the cause of it and how do I stop it from being so thick?

Sounds like a yeast infection

This is a good website for you thinkinleo to find out what white discharge means. If accompanied by itching, then it is a yeast infection. If not, then it is a product of your cycle:

www.pamf.org/teen/health/femalehealth/discharge

By the way I've had this for a couple of years and it doesn't smell or itch.

If it doesn't itch, then it is not a yeast infection. It's probably just the way your body is. If you are concerned, ask your doctor.