Does your campfire have walls, or poles surrounding it? I often place my fires outside along the edge of my structure. I like to wall them in too and make a chimney for them. If you're placing walls around a fire, you're better off placing the walls first and then placing the campfire centered so it's not touching any nearby walls/building blocks.

Even with proper ventilation, it seems the fires will choke themselves if their smoke is not able to escape because of interfering walls or wood poles.

This is how I usually build my fires into a building.

https://imgur.com/lqkSh7x

https://imgur.com/N2EruWc