No problem with nipples - Flickr allows full nudity as long as you mark them correctly for search purposes. Nobody said you should keep the only copy of everything you have on Flickr.
https://help.yahoo.com/kb/flickr/safety-levels-flickr-sln110...
Safe - Content suitable for a global, public audience.
Moderate - If you're not sure whether your content is suitable for a global, public audience, but you don't think that it needs to be restricted.
Restricted - This is content you probably wouldn't show to your mother, and definitely shouldn't be seen by kids.
Guide - Bare breasts and bottoms are "moderate," but full frontal nudity is "restricted."
No thanks. My photos live in four places, and two of them are owned by me.