Sometimes it feels like I HAVE to healbot

Context, im a newer mercy main in bronze

I hear “don’t heal the tank! damage boost more!” All the time.

But it’s Just like I can’t do that. my teammates are taking so much damage and it’s like at some point my only goal is to keep them alive and fighting on objective. :p

I switch to damage boost once and suddenly they’re on like 3hp (I don’t heal full health Allies I do try to dmg boost them)

Should I just trust my second support more and DMG boost more often? Is it situational!? I’m not playing her optimally