How Is HIV Transmitted?

Hello, the other day at work I was exposed to blood from a child of about the age of 7. I don't belive that the blood ever touched me. I also checked my hand for cuts and didn't see any. I used purel after placing the bandaid on. Later that night my anxiety started to kick in and now I'm afraid that I have hiv because I saw the finest little abrasion next to my nail (one of those tiny pieces of skin that hang in the winter). Please help me.