How do you check your cm? Do you observe on panties/loo paper, or do you actually touch your cervix?
All types of cm for those five days leading to ovulation are in fact fertile. Eggwhite is the most fertile of them all, but you can get pregnant with the other types too. Your mucus will usually change in the following pattern and its variations: from sticky to cream to watery to eggwhite.
Now if you just observe on panties/loo paper, it's possible that you don't always notice all types of cm. I usually get the creamy/lotiony stuff there, as well as the watery. Recently I learned that sometimes ewcm is up in your cervix, while you get the watery stuff down there.