Welcome to weight gaming @Dough-E-Nut. Fill Me Up does not have a discord. This is the most active place for discussion on the game. As far as similar games that’s really going to depend on what you are looking for. If you are looking for a female protag with some feedee or gainer elements in the visual novel format. Chunky Cheerleader just had an update on patreon and there is the free demo to check out.
I also have a general recommendations list of some of my fav games based on my preferences that might let you see something new. I’ve tried to include tags and separators that make it easy to find something.
There’s also things like the user maintained list of games. It doesn’t feature everything on the site but might be another way to track down something outside of searching for specific tags.