i used to do metta alot. i use (and still use when i do it) the method in jack kornfields "path with heart". Lately i dont do metta much except for on public transportation. If i catch my self thinking negative thots about my fellow passengers etc i start doing metta for them. if i can catch myself thinking negative thots about anyone (self included) i start doing metta for them.
I noticed some of the patterns in my thinking that you mention above and that notice is, i think, getting sharper and deeper as i continue with it. Tho these days i almost never do it on the cushion, when i did it was pretty blissful for a while. walking around stoned on love is a great way to exist imo
tough to maintain tho.
i got a chance to do some metta today while edging the lawn, i noticed lots of worms in the ground and i probably cut more than a few into peices, so i did metta for them. then it occured to me that "me" doing metta for "them" was just reinforcing the view of separate self, i got a few giggles out of that, and continued cutting up worms and doing metta anyway.
“The truth knocks on the door and you say, "Go away, I'm looking for the truth," and so it goes away. Puzzling.” ― Robert M. Pirsig