AOTC is fucking awful and needs to be removed from the game. My ilevel is 880 and I can't get into heroic nighthold pugs at all for gear. Not even normal ones anymore. It takes me an hour to find a group. And when I do I start seeing the higher geared people who are just in there for AP start saying ridiculous shit like "ONLY INVITE PEOPLE WHO ARE 900+ NOW" or "PUT AOTC ONLY IN DESC". For normal. There are other measures that can be put in place.
One can easily get ilvl 900+ equipped just from running M+, without stepping into any raids.
You're competing with all these people for the raid spot. I'm not surprised you can't get in.
I think you should find a guild...