"I have a house-fire" would be a very matter-of-fact way of saying your house is on fire, but it is technically correct. If instead you mean that there is a CONTROLLED fire in your house, you might say... "There's a fire in the hearth / fireplace." "The fireplace is lit." Otherwise expect the fire department to show up! :) It would seem we English-speakers have a lot of ways to express the idea that one's house is on fire, but not a lot of ways to say there's a fire burning in the fireplace.

Normally, I'd say "my house is on fire". "My house has a fire", "I have a house fire", "There is a fire in my house" do make sense but I think they're not natural.

Perhaps you mean "My house is on fire!"....or better yet, repeatedly scream (not say) "Fire! Fire! Help!"....