They do all appear to be extremely under-exposed backlit scenes. Backlighting tends to fool meters, but if the subjects were in sun and not deep shade then the exposure settings you remembered should give better results.
One problem with discussing light meter apps is that it is the app + the phone that does the metering. For that reason, one person's phone may very well function differently than another person's phone using the same app.
I'd try a roll in even light - a cloudy day is perfect. If those exposures come out well, I'd look to a combination of my metering techniques and the peculiarities of my cel phone as meter.
Otherwise, it may be a problem with your camera and lens.