I counted 16 ending in total

1. If your readiness rating is below 1,750 points Earth is destroyed regardless of the choice to destroy or control the reapers

2. At a 1750 readiness rating if you choose to destroy the reapers Earth is destroyed

3. At a 2050 readiness rating if you choose to become a reaper Earth is saved

4.At a 2350 readiness rating if you choose to destroy the reapers earth is devastated but still there

5. At a 2650 readiness rating if you choose to destroy the reapers Earth is saved

6. At a 2800 readiness rating you're able to create synergy between organics and synthetics, saving earth and the galaxy

7. At a 4000 readiness rating if you choose to destroy the reapers and "saved" Anderson, Shepard lives

8. At a 5000 readiness rating, if you choose to destroy the reapers and did not "save" Anderson, Shepard lives

If you imported a save where the Collector's base was destroyed or you didn't import a mass effect 2 save, then these are your possible ending:

9. If your readiness rating is below 1750 points earth is destroyed regardless if you choose to destroy or control the reapers

10. At a 1750 readiness rating if you choose to control the reapers earth is saved

11. At a 1900 readiness rating if you choose to destroy the reapers earth is devastated but still there

12. At a 2350 readiness rating if you choose to control the reapers earth is saved

13. At a 2650 readiness rating if you choose to destroy the reapers earth is saved

14. At a 2800 readiness rating you are able to create synergy between organics and synthetics saving earth and the galaxy

15. At a 4000 readiness rating if you choose to destroy the reapers and "saved" Anderson, Shepard lives

16. At a 5000 readiness rating if you choose to destroy the reapers and did not "save" Anderson, Shepard lives

As I said people made a lot of assumptions that the endings will be different.

Those are all very small differences, nothing drastically deviates from destroy, synthesize, control, and refuse. An actual quote from the developers:
“This story arc is coming to an end with this game. That means the endings can be a lot more different. At this point we’re taking into
account so many decisions that you’ve made as a player and reflecting a lot of that stuff. It’s not even in any way like the traditional game
endings, where you can say how many endings there are or whether you got
ending A, B, or C.”