The first thing to do if you have a long menstrual cycle is you should confirm that you are not pregnant by doing a pregnancy test. If you are pregnant and you take your temperature then you don't have to continue taking your temperature. 

Normal cycles last between 21 and 35 days.

Menstrual cycles lasting longer than 35 days are called oligomenorrhea (=not enough menses). Menstrual cycles shorter than 21 days are called polymenorrhea.

You should check and see if you ovulated or not. With very long cycles, chances are that you did not ovulate. (What does your BBT curve say?)

Long cycles are usually associated with ovulation problems: It's very likely that there is no ovulation (anovulation), that ovulation is very irregular, or that ovulation is abnormal (egg quality is inadequate). If you ovulate very late in a cycle, chances are that implantation is impaired because both the egg and the endometrium are too old.

• If you did ovulate very late, then you may want to start another graph starting two to three weeks later, and continue the graph knowing that it's longer.
• If you did not ovulate, then you may want to see your ob-gyn or an infertility doctor (reproductive endocrinologist) and find out what's going on.

Your doctor will examine you and see if there is a problem with your ovulation and assess how to treat it. Sometimes your doctor will give you medication to induce bleeding so that you can start a new cycle.