Is It Safe To Have Systen While Trying To Conceive?

Hello doctor. My period cycle is of 30 to 32 days, but I am regular with my menstruation. I had my last period on 9.12.14. After that I didn t had my normal cycle. My pregnancy is -ve. I have consulted a gynae n has been prescribed system sr 300 mg for 10 days. When will I get my periods. Is the drug safe s I am also trying to conceive.