No dominant follicular on day 15. Again.

I am trying to conceive from 1 1/2 yrs. I tried naturally for 1 yr and went for treatment since last 6 months. I was given many hormonal injections but still I could able to have only 2 follicle and from which i didn't conceived. My doctor has lost hope and suggested me to get pregnancy via donor. My husband's sperm count is good. Last month my doctor gave up and she advised me to go for an ultrasound without any hormonal injections or medicine to find out how my body is producing follicles without any medication but to my surprise  there was no dominant follicle on day 15. I was blessed with a baby girl naturally and she is now 6yrs old and desperately trying for a 2nd. Pls suggest me if I should really loose hope to get pregnant again.