Femara and no PCOS

Just curious if anyone else has been here before. My Dr prescribed me 5mg of Femara on CD 3-7 because I have one tube completely blocked and he wants to increase the chance of me ovulating from the open side. I do not have PCOS and normally ovulate on my own. I am on my second round of the Femara but I haven't gotten my positive opk yet (I should have and felt like I did about 3 days ago). Has anyone else taken Femara and not ovulated when they normally do on their own? Thanks ladies!