I’m not going to pretend I’m an expert on Disc, but I’ve been casual pvping a lot this season and yoloing 3s and 2s.
Depth of the Shadows seems to be the most useful trait. Try and stack three of these. Especially in BGs where there are more targets to spread SWP/PtW. As far as I know, none of the other traits are really ‘must haves’. Even DotS isn’t a ‘must have’, it just seems to be the strongest to me.
I usually always run Masochism. Like you said, when two melee decide to train you and teammates don’t help, it’s difficult to stay alive for very long. I would also try and stack as much Vers as possible. Yours is extremely low, but I know you said your gear is a WIP!
Not sure if you are arena or just BGs, but radiance is a huge mana drain. I don’t find myself using it much in arena, except in some emergencies. Has a bit more use in BGs though.
There’s obviously no ‘rotation’ in PvP, but yeah, it’s kinda like you said. Put shield up to apply atonement, put SWP/PtW on as many targets as you can. Smite, solace and penance to do your damage and healing. Don’t be afraid to cast a defensive penance sometimes. Shadow mend is also a very powerful heal, especially with DotS trait stacking.
For PvP talents, i like having trinity and dome of light when doing BGs. Trinity gives you a bump in healing and burst, and dome of light makes barrier into a very short yet powerful cooldown. It really helps against those double melee trains that hurts all of us. Dark arch is usually my third in BGs. The more people around you, the more powerful the cool down becomes.
Other than all that though, it kind of just comes down to CD management. If a double melee is on you, use a CD. It’s not always your fault for dying. If they’re training you constantly and your teammates aren’t helping peel them off, yeah, you’re gonna die no matter what your gear or ilvl is. I know that “use a CD” is pretty basic advice that doesn’t seem very helpful, but modern PvP seems to be all about CD management, especially in arena.