Hi, I have gone through your problem. Thyroid disorder, especially hypothyroidism, hinders the ovulation and hence there is problem in conception.Since you are tking medication for it, chances of getting pregnant are increased. I would suggest you to repeat the urine pregnancy test after one week of the last pregnancy test because sometimes there is delayed conception, and hence delayed detection of pregnancy. If the test is negative, do consult your OBGYN specialist and repeat your thyroid levels, as its derangement may also lead to delayed periods. Hope you found the answer helpful. Wishin you good health.