Assassin PVE issues

I haven't played for over a year but my Hatred Assassin was my favorite build when I was on regularly. I finished that Class. Loved sneaking around and ambushing mobs. Playing counselor I had another in the 50s. Not a subscriber anymore so when I jumped on this year he's locked as an Assassin. Problem is did I forget how to play one?

I am dying constantly in PVE. I checked Vulkk to make sure I didn't have anything stupid in the ability tree, I'm using the recommend rotation, it felt like I remembered how to play the class, but my health just drops like a rock, even fighting basic sith mobs. Did something change? I finished out the Knight quest line with no problems yesterday. Health barely moved even when fighting bosses or champions.

Any ideas what I could be doing wrong or did something change in the last year?

Edit: thanks for all the feedback. Feel better with it after playing around for a couple hours. Couple things seemed to be the main culprits besides getting back to knowing what to hit when.

My companion was set to passive, probably left that way for some reason when I logged. I was outside a heroic when I logged on and just went to nearest quest and forgot I wasn't fighting normals.

And I wasn't using whole toolset. Forgot I could put some mobs to sleep and didn't have to take on the whole group at once.

Really missing the teleport you get later on. And I'd rather be playing as a counselor but I must have logged out as an assassin so I guess I'm stuck.

PS thanks for the downvote for asking a question lol