Why wont the photos i take back up automatically to my google drive?

[AC Question]

I have a ton of photos in my gallery on my phone so i want to delete them from my phone but make sure they are backed up onto my google drive. All of my photos stopped backing up a while ago so i am assuming that is why they are not on my drive. My photo assistant says backing up 1 of 2000 but it is stuck on that and the number of photos waiting to back up keeps getting bigger.