With some caveats, it may not be that you don't trust her specifically, it may be that you are incapable of trusting anyone 100%.

My Domme doesn't do safewords either.

i ran into that, when coming up to the edge of my endurance in a session, it's no fun at all and drags you kicking and screaming out of subspace. The problem is i'm both aching to experience it, exactly as such, again AND scared shitless.

It's something to work on.

po