Period is happening more frequently?

Jasmine
Hi guys, sorry if this is common knowledge haha but it's recent for me so I'm not really sure. 
I had my first period in sixth grade and now I'm in ninth. For the first two years it was pretty regular every month, starting somewhere between the 14th to 18th but then it began to be irregular. It would start on the 7th one month then the 21st then the 18th and back to the beginning on the 3rd and I thought I just had a weird cycle. 
More recently my period has been arriving twice a month at the very beginning then at the end carrying to the next month. I always thought maybe my next month's period would just be early but it kept coming twice a month. 
This month it came even earlier. I began my period on the 2nd of this month and it lasted its usual five days. Then I started again on the 12th or 13th. It wasn't the same cycle as the one from the 2nd to 7th because there was no spotting in between. As usual, the period lasted 5 days so it stopped the 17th. 
Now it's January 24th and my period has began again?
I'm 15 years old and usually can't tell when my cycle is about to start but I did get a headache last night though I thought it was from the kids I was babysitting lol. 
If this has happened to you or if you know what's going on or have any kind of advice or knowledge to share, please do! This is my first post and I really appreciate it :)