I had my period a week and three days ago and I started bleeding today, I have slight cramps. My last period was light what's wrong with me?

Periods. Since you are young it sometimes takes a while for your brain to properly talk to your ovaries and your ovaries to properly talk to your uterus. If you are not pregnant, then these periods of irregular bleeding or spotting may occur until your whole axis matures. There are some that are already mature and still have these problems. Progesterone or birth control pills can help regulate these.