Inb4 someone freaks out about how they'll play how they want: This post is not meant for you. This post is meant for people who are actively seeking to improve themselves. You do you.
That being said! Love to see all the new tanks out on the circuit trying it for the first time, and we need way more of them in M+. I'm going to give you the advice that was given to me when I was struggling to time higher keys (IE breaking out of the 8-10 bracket):
Trust your healer.
I'm hearing the same thing from so many tanks that I used to say:
"I play it safe just in case"
"I worry that I'm doing too much."
"I don't wanna pull more than the healer can handle."
Here's the truth:
If your healer has time to DPS, you can pull more.
If their mana bar is barely moving, pull more.
If they're running beside you or ahead of you, pull more.
It sounds counterintuitive, but if your pulls aren't large enough, you're wasting the potential of your DPS AND making your healer work harder. Obviously, don't pull more than you can physically mitigate on your own. Don't pull multiple caster packs when nobody has an interrupt available. Once you run enough dungeons, you'll start to feel the cadence and get a vibe for what pulls are going to kill everyone and what ones won't.
The moment I let go of that fear and just started getting aggressive with pulls, those big keys started getting timed. Those +1 stars turned into +2s, turned into +3 stars. Aim for the stars, my friends. Trust yourself, and trust your pals. You got this. <3
Love,
Your healer