You should focus on one faction, but not necessarily pure Empire or pure Jedi. The best ships available to you right now are the Geonosians. They won't do as well under Mace or Ackbar as they will under Tarkin. If Tarkin is your fleet commander, then the supplementary ships should be Empire for synergy with Tarkin, Separatist for synergy with your new Geos, or Hound's Tooth which does well in any fleet at all.
All 3 geo ships are in the Galactic War Store where you can quickly take them to 7 stars. There are useful toons in the GWStore, but none of them are worth to you what the Geo ships are worth. However, you do need Heroic raid rewards, which requires a single 7-star character. (You don't need to score well, just to qualify.) So the best thing for you now is raise one character from the GW Store to 7* & after that spend every single GW Token on the geo ships until all 3 are at 7 stars. Cad Bane, Biggs, Zeb, and Poggle are the best candidates for this 7-star treatment.
In the fleet store, purchase shards for Vader & blueprints for Vader's ship, the TIE Advanced x1.
In the Guild Store you should be purchasing Sun Fac until he is 7-stars.
Your Cantina Energy should go to farming Geo Spy & Geo Soldier. Gear up Tarkin while waiting for them and Sun Fac to reach 6 stars. Once any Geo hits 6*, you can begin devoting gear to them. Take them all up to g8, at which point you can begin using them as your Arena fleet. Keep gearing the Geos until Spy is g11, Sun Fac is g10, & Geo Soldier is g11. You'll want to take them even higher, but right now we're setting reasonable goals for a reasonable amount of time in the future. When you get all this done, you can reassess & make new goals.
Now, that all said, I also worry that your guild may not be completing the heroic raids. When playing a game, fun should always, ALWAYS be first priority. If you're in a guild with good friends & you're enjoying it, go ahead & stay. But if you're interested in making progress in developing your characters and you don't have strong bonds of friendship keeping you in The Sisters of the Force, I would recommend moving to a new guild right away. The rewards of a good guild's raids are invaluable.
If you'd like help on how to get into a guild which can better help you progress, let me know & I'll write about that.