This happened to me last year.
Even if you don’t have an ADHD son, always invite more people that you need.
I only had two RSVPs at my son’s party a couple of days before his birthday and lots of nos.
I started messaging on neighborhood sites, guilting neighbors to bring their kids to the party. I got about 3 RSVPs. When I got to the Chuckie Cheese, I asked adults at the restaurant if they would be interested in letting their kids join in the fun. I offered to buy their food and give them tokens.
So, I think we had five kids total. Next year, I’m planning to do a special day somewhere, so that he can invite a couple of friends