What Causes Watery Pink Discharge On Random Days?

Hi, I'm 26 years old and I've just started taking yaz, ive still got a week left till my period and my husband and I have been having sex 7 days into taking the pill.. I've been getting watery pink discharge on random days .. I started taking yaz because my periods have not be regular for the last 3 month.. I would get spottings for about 3 days then my period for 4-5 days and spotting after.. They used very regular, not sure where I went wrong.. I'm married with 2 children.... So should I stop taking the pill, take a pregnancy test ? Not sure what to do.. I've never had this problem before..