What Is The Cause And Treatment For Infertility?

Dear Sir / Madam, We are in baby making plan since last 8 to 9 month. My age is 22 and hus is 30. My period is not always normal and had consulted infertility specialist last month(09/07/16). Doctor advised Fertisure F for 3 week. I took this tablet only for one week and I just had one yesterday. My date is due on 26 and now delayed for 4 days. We just checked home pregnancy test this morning but it shows negative. Could you please advise the reasons, is it because of that I didn t continue medicine for 3 week or other reasons. .do I need to wait or consult nearest gyn dr. Your kind advice would be highly helpful and appreciated. Thank you !