This was similar to me. I had very irregular periods until I was 18. I went a year and a half between periods at one point! Keep track of your periods and if you are sexually active it's allllways good to get checked for STI'S some of them can affect your period. If you turn18 and you're still experiencing these irregularities visit your gynecologist and he/she can help try to regulate your cycle! Try not to worry too much right now but like I said, keep a calender to keep track of your periods and any symptoms that you feel ! I hope this helps :)