I won't give away how to find the endings, but so far you're missing endings 5, 12 & 13. Ending 5 is in the Pres Tubbo storyline. Endings 12-13 are found in the Pres Quackity storyline, if you prevent war from breaking out in chapter 3.
Also remember that for a few endings there are more than one way to find them, so watch out for those!