Can't sync new songs to my iPhone, because my photo count is wrong

My photo count on iTunes says 4,450 photos (15.23GB) when I really only have 1,799.

On my iPhone, in settings, under usage and manage storage, it says for photo and camera theres 15.9GB used; but I've deleted many photos and videos.

I only have 1,776 photos and 91 videos. If you count snap chat, instagram, instasize albums it would not add up to the number shown. Help!