If he was just exceptionally gentle, or you were lucky enough to have an exceptionally thin hymen and went fast enough that you didn't notice.
Having unprotected sex with someone you barely know or even if you do know them well can lead to pregnancy and possibly life threatening diseases.
The general idea is that once you have penetrative sex once a man has entered you with his penis you are no longer a virgin.
The first time he did it, it didn't fully get in and then then the next time I climbed on top of him and we did it for a minute or two.