To slip inside you without you feeling it going in?

Sorry for being so blunt, but I recently lost my virginity and I didn’t intend for it to happen, he just put it in and it happened so fast. I didn’t really feel him putting it in. No I wasn’t drinking or smoking anything and I am not a naive teenager lol. I’m in my twenties...

EDIT: He is medium sized and no I don’t use tampons.