Sounds like you are on the right path. I tend to stick with Eos, and I cycle through her cooldowns fairly aggressively to maximize my dps uptime. Even with Selene, I'd recommend keeping her on obey, so that you can manually embrace for higher hps, and again, more dps uptime. Leaving Selene on sic however isn't a too terrible though, she does manage her own buffs fine, but I find mismanaging her buffs once in a while is a worthy sacrifice for embrace spam.
For DPS'ing, I go Bio II > Miasma > Bio, in descending order of DoT duration. Since Bio has no cast time, I'll bane here, or energy drain if it's a single target, then start applying Aero on mobs, starting with the target that has the lowest health left. I tend to use an Aetherflow stack with every Bio, since it lasts 18 seconds, and will keep you regularly using stacks without burning them too quickly in 60 seconds, and without letting them pile up. If I have unneeded Aetherflow stacks, I try to burn them on Aero casts since, like Bio, it has no cast time.
Pre-buffing right as the pull ends is a great practice, and if you cross class Stoneskin, it's nice to throw that on too, time permitting. For in battle Adloquium use, I use it as a one off heal, to provide a buffer while embrace, and possibly whispering dawn patch up the rest, and I can return to dps, or to slow down incoming damage when I need to patch things up, be it healing the tank or leeching debuffs etc. I only cast Physick when spot healing, or when my target is already galvanized.
Also, healing is largely based on your decision making ability. Unlike dps where you follow a rotation (you do have a damage rotation, but you also have other responsibilities), you need to know your toolkit to know what to use when. That said, experiment with different things, try healing in different ways, be open to suggestion and constructive criticism, and develop a strategy that works well for YOU. If you can reliably keep everyone alive, even through mistakes, patching up and preventing wipes, you are doing well. If you can add damage on top of that, great bonus.