Helpful Google links
Your account
Storage (includes Drive, Gmail and Google Photos):
Google storage (your usage).
Google storage management (What uses most storage?)
Google Drive Quota (What uses most storage at Drive)
Google Photos forums
Blogs
Picture this: A fresh approach to Photos (Official announcement of Google Photos)
Changing how Google Drive and Google Photos work together (Official announcement)
Updating Google Photos’ storage policy to build for the future (Official announcement)