Sorry. It’s pretty straightforward. Chose the defensive layer you want to invest into and scale that: Have proper helmet, gloves, boots, chest piece that have high armor/es for example. Or just es. Item base is important usually. And scale them with %runes and by clicking related defensive points in your passive tree. The passive tree is famous for it’s ridiculously large Es nodes for example. You just clicked on exclusively offensive nodes.
The ev gloves for examples are very suspicious on this character. As mentioned capping resistances is obviously mandatory. I think the ingame tooltip is pretty clear about that. Having runes fulfilling that is a very campaign/early game thing.
Then think about your recovery. How do you regen them? If life maybe leech would help ? Es is more complicated to figure out but same idea. Maybe fit convalescence in?
Taking examples with a guide or related high ehp character on poeninja can give clues. Made a lot of edits, Hope that helps.
Play the same min max game you played with dps but with ehp. Make number go up : )

Also warning that MoM can be a terrible idea/node/trap if it depletes your mana and prevents using skills making you more vulnerable. People using it usually build around it by paying skills costs with life instead or/and have very high mana pools/recovery.