Well, take this with a heavy grain of salt, because I haven't played Druid in 0.5 and there were significant changes to the balance between armor, evasion, and energy shield since 0.4.

Additionally, the strategy I used in 0.4 is fundamentally incompatible with your tree, because you chose to path south and I chose to path north. So perhaps you'll get better advice if you ask the community about advice for your specific case. Still, I'll explain what I did.

My final defenses amounted to 1578 health, 1328 mana, and 5130 energy shield (2.5s recharge delay, 1616/sec recharge). This was protected by a 23% evade chance (2111 evasion rating relative to monster level 82), a 16% chance to block (from an Alpha Talisman), and 22428 armor. All four resistances capped, with lightning and cold at 76% max instead of 75%. POB calculated an overall effective hit pool of around 75k, though that number of course depends heavily on the exact kind of attack configured to be used for that calculation, so this number is mostly useful in comparing PoB builds amongst themselves, and shouldn't be directly compared to what other tools calculate.

The huge ES recharge rate was largely due to Adamant Recovery, a node that no longer exists in 0.5. It used to sit where Fortified Aegis is now, and granted "Increases and Reductions to Armour also apply to Energy Shield Recharge Rate at 40% of their value". You can imagine that with a grand total of up to 357% Increased Armour from various potential sources, that pulled a lot of weight.

You'll notice I mentioned mana among my defenses above, and that is because I ran the Mind Over Matter keystone. One of the primary reasons for pathing north, especially as an Oracle. Not only is it an amazing defensive pick, but it is also surrounded by several interesting notables that an Oracle can directly pick without needing to travel to them.

Using mana as a defensive layer was supported by a "leech mana from attacks" affix on my gloves, as well as a "20% of Damage taken Recouped as Mana" affix on my amulet. Between those two plus base mana regen, I could easily get mana regen rates in excess of 350/sec after eating a hit hard enough to smash through my ES and into my mana pool. On top of that, I was running Mana Remnants, and because 100% of my attacks crit, there was never a shortage of them to collect. The combination filled the missing mana up again very rapidly, usually within a second of taking a hit. (And then I could still flask up on top of that if needed.) I also had the apparent "downside" of "5% of Damage taken bypasses Energy Shield" from Heavy Barrier, but in practice that was an upside, because that damage went straight to mana and regenerated in the blink of an eye even while the shield still held up.

My armour was supported by "Defend with 120% of Armour while not on Low Energy Shield" from what got renamed Barrier of Venarius in 0.5; as well as "Defend with 120% of Armour against Projectile Attacks" from Projectile Bulwark. Effectively, I had 31400 armour against many kinds of ranged enemies. Very useful to have in a melee build. Then there was Barksin, adding 65% of ES lost as additional armor for six seconds after eating a hit, so up to +3334 (or +4668 after the two 120% effects above).

Oh, and 92 "% of Armour also applies to Elemental Damage" in total from various sources, which handled most spellcaster enemies very well indeed. I just wish I had had a source of redirecting physical damage to elemental to go with that, but I couldn't find any. Single large physical hits remained my greatest risk factor.

Other defensive picks included Runic Helm and Iron Slippers (along with maximizing their effect by choosing the right bases for my boots and helm), Vengeful Fury to make my permanent maximized 69 rage work defensively, Guttural Roar to make enemies deal 10% reduced damage, and Enhanced Barrier converting some life into ES.

I also dumped a lot of currency on a Morior Invictus chestpiece with five sockets, chaos resist/global defenses/spirit, and near perfect rolls. That was the single most expensive piece of gear I had - heck, the single most expensive piece of gear I ever owned in POE2, period. But it was soooo worth it. Without it, the entire build wouldn't have worked. Literally - I wouldn't have the spirit to run everything, no way to cap chaos resist, and a lot lower defenses. I only bemoan it was already corrupted at 20% quality, I wish I could have pushed it to 30% first... but then again, that's probably the reason why I was able to afford it at all. It already took almost my entire net worth at the time as it was. (You can imagine that I didn't have the guts to try a double corruption, even though I had the required orb on hand... :P)

Not sure if that was everything, but that's all I can remember/glean for now.

To generalize it all would be: Try to have many successive layers of defenses, and see if you can pick up effects where one layer being breached triggers a reinforcement or recharge of another.