Would have been nice to have a second reassurance. I did do a bit of research on the different tests when you listed them below to see if they do things differently (I am in genetics research so these things interest me!). Harmony had a nice website explaining things and it seems the MaterniT21 test uses Massive Parallel Sequencing, whereas Harmony uses more direct sequencing (although they didn't explain), I couldn't figure out how Verify does it. Anyway, Harmony claims their method is more sensitive so potentially you could get a result from them? Just a thought.
You are probably done with all this and I agree, if you feel ok then go with it. I am a bit the same as I didn't get the greatest odds on the nuchal but I think I can live with the small chance that the baby has ds. I have the level II tomorrow so I guess if they pick up some markers I will have to reevaluate.
Definitely no certainties in life, heck autism rates are around 1:60 for boys but nobody stresses about that because we can't test for it. Hang in there!