I can relate to how scared you were. HRH pulled out of a harness shortly after we first got her.
It was this type of harness that had a yoke that wasn't adjustable at the chest and the waist didn't tighten enough to hold her. View attachment 51554
We switched to this step in harness that seems much more secure.
View attachment 51555
We don't ever use collars on the girls. We have heard way too many scary stories about them hurting bully's windpipes so we just won't risk it.
The step in kind is what we use. It is great but you still have to be careful if they back up and pull.