Something you have to keep in mind with anything more difficult than T4 is that EVERYONE has to pull their weight in order to clear these fights. You cannot sleep through them until you've done them enough times to know the mechanics by heart. Also, the entire group has to agree to run the same strategy. If half of your T5 party is used to running with a single-tank, they're going to do things differently than a party that's used to dual-tanking it, and everyone is going to ruin the run.

Just looking at your lodestone profile, you do know that the necklace and earrings that you're currently wearing are supposed to be for DPS classes, right? You're missing out on at least 30 points of Vitality, which is a little less than 500 HP.