It is not the tense that I an worried about. It is the meaning of the verb “hold”. “Hold” means “organize”.
I think “to hold a party” means “to lay out chairs, table and put other decoration etc”
So, “I am holding the party” means “I am laying out chairs and putting decoration etc”.
After everything is in place. The party is not being held.
The “party is being held” must happen before the party starts
Can I say "I am holding a party" when the party is happening and guests are celebrating?