Hi, are you on the pill?
Are you using cronometer to track your fat intake? Your period should get lighter the cleaner you eat. I am wondering if you are eating too much peanut butter! :D A high fat intake is actually pretty common when first starting out because it's tricky to get in enough calories so people get hungry and eat fatty stuff, also people don't realize just how much fat they are getting, it's very easy to go over 10% of calories.