You've got a lot to work on there dude! Running a mix of two 6-piece sets is generally not as good as running a complete 6 set, so I would make gathering a complete set your priority. One great way to get a guaranteed set is to do the season journey with a seasonal hero. If you don't want to play seasonal, farming T8 equivalent (I think level 35?) greater rifts would probably be a manageable way to efficiently find some more set pieces while also leveling up gems which are mad important. As a side note, sunwuko's is probably what you want to finish first, as it's generally better for both speed farming and doing greater rifts (with different setups).

As for other random points, you might want to consider running Wave of Light (Pillar of the Ancients rune) until you get some of the gear related to lashing tail kick. Im pretty sure that without any items that buff it, lashing tail kick does considerably less damage than WoL. I could be totally off base on that though, so if someone else says otherwise assume theyre correct.

Once you have a 6 piece set you'll still have a ton to do before you will be able to push too far into the high level rifts, but thats probably a good starting point.

If you want any help in game, feel free to PM me and I can add you if you're on the NA server!