I Have Been Refered By A Docter To Be On

I have been refered by a docter to be on the trigestrel pill as I have irregular period and have been trying to conceive for more than a year now how does the pill help me to conceive and what is the funtion of each tablet and how long will it take for me to get pregnant after 3 month of stoping the contriseptive as he told me to stop after 3 months