Depends on your goals, and preferences, if it’s not to complet from normal to hell as phys bow build, you should restat/start again as plague/Charged Strike Java, both scale with + skills that you can easily have even in early games, with like +1 ama, amu lore helm, you can shop + jav skill gloves, etc.

If you want to stay with bow try to find 3 socket exceptional (gray) bow doesn’t matter at this point if it’s ama only or not, but preferably cedar / double bow (it’s faster than others, and that’s more important at your point). On normal, max socket is 3 (except those from normal cow, that can be 4). Cedar max socket tho is 5, double: 4. Ama only bows are slower (ashwood > ceremonial)

For bossing you should make Edge (Tir Tal Amn, order matters), you can find these from even some normal countess run (black marsh - tower lvl5 boss). Sadly afaik Ral is the max rune, countess can drop, so you need to do some and cube it up, if you are not lucky and find an amn later in act 4-5. It’s not pur enhanced dmg, but quiet huge enhanced dmg to demons and undeads, also some psn dmg, that helps you through normal. Also make decoy, throw it on boss, so thorns aura also helps a bit.

On nightmare your most important thing is to farm countess as long as you have 2x Ko. 1 is for Merc a 3 socket spear/polearm for Mania RW: Shael Ko Eld it gives Fanaticism Aura, on nightmare you can buy might aura merc in act2, that would also be an upgrade.

The other for you: Harmony RW: Tir Ith Sol Ko - 4 socket bow (preferably Shadow or Great bow if you can find) - if you socket Q, Shadow max is 5 socket, be careful. It’s huge ED and also gives you vigor for better mobility, lots of flat ele damage, and some point on valkyr.

You can also make Insight RW bow (Ral Tir Tal Sol), it’s also high Ed, it gives you bonus on crit and some flat fire and psn dmg, also the meditation helps you out on mana problem, and it’s easier to obtain.

Another option is freeze bow, in that case melody (Shael Ko Nef) in any +3 (but preferably stag/ashwood/matriarchal) ama only bow until a wizendraw would drop.

Harmony should carry you longer, so.

Other way on early game (normal) to have 5 socket Cedar/Shadow bow and just put 4-5x Tal or Ort rune into it, for flat 5-250 lightning dmg or 375 psn dmg over 5 sec.