I'm not sure if the challenge was wrong or not, but I have previously done this question before and it seems I got the same answer as yours. I belive there is no problem in your solution though.
@Bella Nice! 😄 That's definitely a valid way of doing it-- splitting into cases based on whether the triangles are equilateral, isosceles, or scalene (no two sides with the same lengths) is a good choice, because then it makes it harder to accidentally miss a triangle. Just goes to show that there are often multiple ways to solve a problem!