That all checks out, but which QTE are you experiencing problems with? Was it one from when Killigan is lying in bed during the prologue, one from the middle of combat, somewhere else?
During the fight with Elise it doesn't matter how high my brawn is, the gauge doesn't increase. The highest (armor included) is at least 17.
With the clutchmates there is a bit of a difference, but it didn't change the outcome. By this point by including armor collected I had at least 30 brawn.
So I don't know if the stat is low for these points in the story or if the requirments for completing that particular QTE are just ridiculously high.