NO ONE actually considers Washington Heights part of Harlem. EVER. You’ll never find a single map ANYWHERE made by ANYOne saying that. The rest, sure. You’re mixing up “upper Manhattan “ with “Harlem”, in which case you’d add Inwood. But all versions of Harlem end at 155th or lower.
See this NYT article which discusses the MAXIMUM area ever considered Harlem:
https://www.nytimes.com/2010/01/06/nyregion/06harlem.html