A 28-year-old woman from Delhi presents to the infertility clinic with a 3-year history of primary infertility. Her husband's semen analysis is normal. Pelvic examination is unremarkable. Transvaginal ultrasound shows a normal uterus and ovaries with antral follicle count of 8 per ovary. Serum FSH on day 3 is 7.2 mIU/mL, LH 6.8 mIU/mL, and prolactin is normal. She has regular 28-day cycles. She is counseled about ovulation induction and started on clomiphene citrate 50 mg daily from day 3 to day 7. On day 12, transvaginal ultrasound shows a single dominant follicle of 18 mm with endometrial thickness of 7 mm. What is the most appropriate next step?