anytime when you are taking
fertility medicine, you chance are having twin. Most of doctor already do the best he/she can to help you. There are a lot of reason why you can't have a baby even though your test come back normal or above normal. If you feel the doctor didn't do the job, then go to specialist (RE) for treatment.
Stress, poor diet, weight, age, uterine fibroids, health problem, athletic training, etc... there are so many factors why woman can't conceive.