Relatively new. Trying AST. Need serious help.

[TakumiHarada]

AST is the weakest 4-man healer imo, and with Holminster it's especially bad.
Your only instant burst heal is the 1 SINGLE essential dignity per 40s, and your other heals are either regens or delayed.
Compare that with WHM having tetra+bene+lilies per 20s and SCH/SGE having lustrate/excog/duro/tauro per 20s + free regen.

I use the levelling roulette quite often and play different healers randomly, and AST+Holminster is THE ONE that I actually need to use Synastry+Benefic II (basically the last resort for AST) and still barely catch up.
I don't think it's your or the tank's fault. AST is just bad at that particular level.
It gets easier at higher levels.

[IDontPetLalas]

AST is the weakest 4-man healer imo, and with Holminster it's especially bad.
Your only instant burst heal is the 1 SINGLE essential dignity per 40s, and your other heals are either regens or delayed.
Compare that with WHM having tetra+bene+lilies per 20s and SCH/SGE having lustrate/excog/duro/tauro per 20s + free regen.

I use the levelling roulette quite often and play different healers randomly, and AST+Holminster is THE ONE that I actually need to use Synastry+Benefic II (basically the last resort for AST) and still barely catch up.
I don't think it's your or the tank's fault. AST is just bad at that particular level.
It gets easier at higher levels.

Weakest ?- it depends upon the person as well.

I've never used synastry in Holminster and hadn't an issue (aside from my first run which was quite interesting levelling) however that doesn't mean that it wouldn't be a good idea to do so with a specific group (e.g. tank that's undergeared). As you say there's only one charge of ED, in the past if people stayed out of your star, it could get really bad and lead to a wipe, but that should really not be an issue now. Clearly you don't have access to some of the really good heals like macro at that level however you do have access to additional instant heals CU, CO - and some (limited) mitigation.

[TakumiHarada]

I mean... Not to get into details because it's OT but objectively AST has:
- the lowest total potency of free heals for the tank (except maybe Macro depending on how you use it, but WHM also has Bene and its free heals have higher total potency over a minute)
- the lowest rDPS in 4-man dungeons, by quite a margin
When the total DPS is low and the wall-to-walls take forever, an AST will need to start using A.Benefic/Benefic II earlier than the other healers. It has fewer free tools to fall back on.
It's totally OK to use A.Benefic/Benefic II because no one actually "optimises" dungeons, but it worsens the low DPS further and the fight takes even longer.

It's a good job for 8-man raids, I sometimes play it for the excitement in dungeons as I said before, but I mean,
if you play all healers in 4-man dungeons you'd know WHM/SCH/SGE are just easier to keep the tank alive, especially when you're paired with a non-WAR who doesn't use their mitigations.

Not to mention OP was at lv72 which is one of AST's weakest spots I'd say, before getting CI & double EDs.