Period Help!!!!!!! 13 years old!!?

I started to spot last thursday and started my period Friday and ended today. It was midway heavy. Im 13 years old. I have never had a boyfriend or have had . Would someone please get me to believe that I'm not pregnant and that was not implantation bleeding. I'm just can't get that out of my head and it is driving me insane and I am getting ready to go vacation and I don't want to worry the hole time. Please tell me things to get it out of my head. Please help me :(