Your Google Photos storage would be zero if you chose to store them at "High Quality," which is actually compressed (though very good quality still). My guess is that you haven't actually emptied your Gmail trash yet and therefore it is still taking up storage. It may take a day before the reduction in size is recorded after emptying the trash. There is no contact information for Google unless you already subscribe to Google One. The only option with Google is to ask for help on the community forum, but they are not official Google employees there. If you pay for Google One there is support that can be contacted. By the way, if you click on the amount of storage used within the Gmail web interface it will take you to a page with more detail on what is taking up space. From there you can click a link to go to the Storage Manager, which helps to determine how to gain more space.
https://one.google.com/storage/management