I honestly believe the main issue is that Moira and Mercy have a getaway and better self healing. Ana is stuck no matter what. And how crappy is it to have to waste your grenade on yourself? Or even have to run to your team to get a decent group grenade (to heal yourself and them) only to be caught in the line of fire.
Ana needs an escape or mobility. Why cant sleep dart turn into like “adrenaline rush” where Ana self injects herself and has like 30% increased movement speed for 4 seconds or something?