One recommendation - you really seem to undervalue Aegis of the Legion. It's immensely powerful if you build it in the midgame, as your first major item after philo stone, heart of gold, and boots. It makes an enormous swing in midgame teamfights, and provides you with a lot of personal survivability as a support to prevent you from being bursted out.
As for the rest of it - I find that supports actually get more abuse than most roles, not less, because it's harder to make it really obvious when you're playing brilliantly unless people are fairly perceptive. Like at 1400 Elo I've easily carried teamfights as Sona with an ult across all 5 targets, peeled someone off a carry with a powerchord'd E on a carry, helped burst someone out, tanked damage until I was at 5% health and then flashed through a wall, and continued to fight with Qs/Ws through the wall until we ace them without losing anyone, and no one will even notice. Meanwhile, you can deliberately take a skillshot that would one-shot a carry and die, and you'll just get people saying in all chat 'noob support, team too heavy, can't carry' or whatever. You just need to blow people off. Frankly, I think the role that gets the least abuse is top, because if you just farm your lane and never die you'll have zero impact in a losing game but people will find it hard to blame you for anything, even if they really, really should.