HELP-please answer!!

Maisy • 17//
I'm 17 and for about a year now I have have continuasly got puffy nipples. When I just get out the shower and turn cold they lose puffiness and turn normal, but after I've warmed back up again- they turn puffy. They look so horrible and it makes me insucure to take my bra off during sex, I was just wondering what this is and does it go away?? I was a late starter to all other purberty factors and was wondering if it could be related to that??