Innie or outie nipples......

Okay so my boyfriend saw me topless for the first time and had a weird shocked look on his face. Im a D cup so I know it’s not because they’re tiny or huge. Basically he said my nipples were innies?!? What the fuck does that mean?!? I know my nipples don’t look like those of some girls but am I a freak?!? Im super stressed and now SUPER self conscious. Does anyone else have or have seen this? Thanks