Don't worry, it can take a long time! Mine went on for over a month. I finally ended up asking for some used media for my filters on our local fish forums. Once I got that, it cycled in 2 days.
I was always told not to change the water until it's cycled, then do a large >50% water change and add fish.
But listen to Diana, she forgets more than I will ever know! But yes, it can take a long time.