Why didn’t my first time hurt?

Im 18 this month and my first time was yesterday. We had sex in a couple different positions. It actually didnt hurt at all and it was just really enjoyable the entire time. Is my vagina just big? I hope not. But i masturbate a lot so can that be the reason it didnt hurt? Did i just stretch out my vagina? (Btw i use ultra tampons for my heavy flow sometimes)