My af cycle keeps getting longer first 25, 28, 3, 38 days cycle. am ttc and would like to know what could be causing this and what can i do to fix it?

Ovulation: If you are trying to conceive you shoul not care how many days there is from one period to another. You should be trying to determine if you are ovulating or not. A home ovulation kit would tell you this answer. If you're not ovulating you need to see a doctor for help. If you want perfectly timed menstrual cycles birth control pills are your answer.