cd 19 still bo positive OPK :(

[smemma]

Hi ladies, I am on cd 19 and using opks. I havnt had a positve yet and to be honest in the 10 mins mark of having to read the opk there has been no LH line hardly.. maybe if I squint! If I come back to the test after about 20 mins there is a darker line. Yesterday and the day before I had a lot of ewcm but no positive opk I have thyroid problems so this is worrying me. Has this happened to anyone else x