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."