I Have Problem Being Pregnant. Last Time I Undergo Transvaginal

I have problem being pregnant. Last time i undergo transvaginal ultrasound. our community doctor said that my endometrium linning is thicked. So i consult an obgyne. She prescribed me a pill specifically that "liezl" for my menstrual period to be normal because that time im irregular.. But i didnt bought it because its too expensive. now, my menstration is normal but till now, im not getting pregnant. What's the problem?