I was taking 100mg Clomid (clomiphene) from day 3- 7. My progesterone level is 3.6. on day 21. Do you think I should take stronger medication, or should I go to the fertility specialist, because right now I go to gynecologist.

You may. A progesterone level of 3.6 (day 21) implies ovulation. However, your doctor may either continue your current dose of 100 mg or increase to 150 mg to increase your chance of pregnancy (superovulation). Note, most women who are going to conceive on clomid (clomiphene) usually do so within the first 3 months. Therefore, a trial of 3-6 months on clomid (clomiphene) is reasonable before seeing a specialist for more potent drug.