Have I started my period?/Is this normal?

Hi. I'm 13 and I desperately needed the toilet at school 2 months ago, so I went, but when I wiped, there was only blood and, because I wasn't prepared, when I got home, my knickers were covered in blood. There was only blood for 6 days after that. Was it my period? Also, if it was, 2 months have gone by and there has been no sign of it happening again. Is this normal???