What Causes Infertility With All The Reports Being Normal?

Hi, I m 28 yrs and 4 and half years of marriade i had two abort. but now i want to concieve my gynaec told me to take fertyl tab for 5 days today i will be doing the sonography. I had my periods on 8th of feb and on 12th feb I had my urine,stool and sonography of pelvis done and the report was normal.