What's better? Femara (new) or higher dose of clomid (3rd cycle)

I tried 50 mg of clomid in November (CD 5-9) and December (CD 3-7). I didn't get pregnant with either. I do ovulate weakly and late without assistance normally but we have been unable to get pregnant so my doctor decided to assist. She never tested my progesterone levels for either cycle but we assume I ovulated due to positive opks. I didn't try anything last month and still no pregnancy. We have one more month to try before I have to go back on birth control for my endometriosis. Do I ask my obgyn to up the dose of clomid or to try femara? I read that femara might have better success but i don't know if I should basically start over since I have already been doing clomid. Any insights?