Why i'm not happy with going as a Tank Support anymore

Truth be told, I love ... she is my main. Being a tanky support and taking on the world is how I got to Plat 5 last Season. Everything about being able to take on the entire team and come out alive was always a great feeling to bear. However as time went on, no longer can I even manage to survive much of anything anymore. This is not me saying that Tank Supports are no longer valid, because they still have great uses ( with his shield, with his headbutt / knockup, ect.) but as it comes to being tanky ... they don't feel tanky right now.

AP Assassins can easily destroy me now, despite building and such. Granted I know i'm not supposed to be as tanky as a top laner or jungler who's but even still, the lack of defense is clearly showing itself. I have to ban now because she shreds my armor and can 3 shot me even if the ADC is behind late game. How am I suppose to save / protect my allies if I can't even survive most of the damage now?

I feel like Riot's been buffing damage, but not providing us tank options due to how Bruisers / Divers have been taking advantage of such things (like how has been using Colossus Keystone) and how items like got nerfed quite a bit because it was too good at release. I feel like in order to be useful as a Support, I instead go with champions like because items like (basically utility / mobility / ect.) are what is working well. I just had a ranked game where I didn't die and did more for my team than what I could as a tank support. This saddens me, I want to provide my team with a good tank support but not die like a squishy .... le sigh