I'd say they're fine. My ears were also originally pierced low-ish (when I was 7), and I've successfully made it to 5/8" without visible thinning (and no downsizing). If oils bother you, get a basic unscented lotion like lubriderm and use that for massages...it's the act more than what you use that helps increase circulation. Honestly, I've you've already downsized without a whole load of success, doing it again probably won't help all that much either. You're obviously conscious of the health of your ears, and know the warning signs, so just keep an eye on them and keep taking care of them and you should be alright.
If you live in a boring house, you might as well decorate it.
5/8" lobes x2, 10g/8g lobes x2, 12g conch ridges x2, 16g anti-helix x2, 18g nostrils x2, 14g centre lip, 10g septum, 10g left flat, 24 tattoos, lotus & pistol branding
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