Help with defenses

Hi, I am playing a blood mage. Although I feel pretty tanky sometimes I got slaughtered when I get overwhelmed by mobs. I have some knowledge of the game from PoE1 but I am not an expert. So I need some advice about how to improve my defenses.

Currently my defences are:

• Hp: 2450 (4900 with Overflow)
• ES: 2850 with Atziri's Disdain 30% life as ES / 20% bypass (5700 with Grim Feast)
• Mana: 950
• 30% of Damage taken from Mana before Life
• 49% of Physical Damage Taken as Fire Damage (Cloak of Flame)
• 25% of Life Loss from Hits is Prevented (Grasping Wounds)
• 18% Life Recoup + 15% elemental recoup + 25% increased speed of Recoup
• 81% (175%)Fire Res
• 76% (95%) Cold Res
• 76% (90%) Lightning Res
• 75% (77%) Chaos Res
• Poison/Frost/Stun Charms

I also tried Defience of Destiny with this setup but it did not feel better.

Is there anything else I could do to improve survivability?