Ive had my period already this month and now its back the same month?

Once a year?: A woman with cycles shorter than 29 days (shorter than 1 month) will likely have 1 ovulation per month during the year, but have 2 ovulations during one month of the year (since she has about 13 cycles a year). That means she should have one period per month, except that during one month each year she will have 2 periods. That's the only way to fit 13 regular periods into 1 year.