EWCM but negative OPK?

Annabelle
Help! I'm CD13 today, I normally ovulate between CD14-18.. I've been getting a lot of EWCM since yesterday but my OPKs are very negative, not even close to a positive. I am using internet cheapies though so don't know how much I should trust them? I'm not sure if this means I've missed my LH surge or I'm not ovulating yet. Any advice? Xx