It's obviously big enough for the dining table and chairs. The lounge suite might make it too crowded, especially if a lot of people are moving about, bringing food, visiting, etc.
I would just put all the furniture where I think I want it, then pantomime how it would be used, and see how comfortable that is. If it feels cramped or you're falling over things, move the furniture farther apart. When it feels right, measure the space that takes. If it's more than you have, decide which furniture has to go.