What Causes White Discharge From 19th Or 20th Day Of Periods?

I am trying to conceive. i m 26 years and my height 5 ft 5''. wt is 73 kg. i ve taken follicle study in 2 cycle. as my doc priscrip, i m taking syphiene om ny early days of periods and duphaston during 18 to 25 days of my period. i mgetting white discharge from my 19 or 20 th day of my period. y this so? am i get pregnant.