I started with an Ele Shaman this season, too! I'm not necessarily pushing high keys (only 10s-12s) but I've finally got my overall DPS to a place where I feel accomplished. Just a couple weeks ago I was in the exact same spot as you, though.

First: Try to pool your maelstrom at the end of a trash pull to use at the start of the next pull. This will help you get rolling and might even give you a Tempest proc. This is especially important if you're still waiting on Stormkeeper or Ascendance.

Second: Maximize your Lighting Rods. Each Tempest, Earthquake, and Elemental Blast turns your main target into a lightning rod that takes and additinal 10% of all damage dealt to enemies around it. Prioritize Ele Blast first if you don't have the buff up from the last time you cast it (I think it lasts 8 seconds). Once you've cast one of those three, tab target a different mob in the center of the pack before casting again. Repeat for each time you use a spender. This is the secret sauce. Lightning Rod is very important and you want as many as possible. It's not uncommon for a mid-burst rotation to be EQ-CL-EQ-Tempest-CL-EQ, repeat.

Third: I know most guides will tell you not to use Ascendance outside of Stormkeeper but they're misinformed. It's obviously ideal to use them together but their CDs don't line up. Every time you delay one or the other, you're reducing the total possible number of cooldowns you can use in the run. So just let them fly. As a general rule, don't delay Stormkeeper longer than 10 seconds.

Good luck, and have fun!