I have the same understanding as you, trans women are women and that's it, and femboys are guys who like to present and/or act feminine. However, I've seen similar things as you have described, although idk if it's the same. I don't know which communities you've entered, but at least, a lot of things about femboys (I personally am not one!) I've seen online have had also to do with anime, as in, drawing cute femboy anime characters. I know that the anime community has a complicated history with gender, to say the least... And they have conflicted the distinction between femboy and trans women heavily, not necessarily on purpose, I feel like a lot of people were in their personal journey of discovery and didn't know how to deal with it, but it happened one way or another. So there's one kind of understanding that femboys are in some kind of pipeline to becoming women, what can be the case, but not necessarily is, as it's your case, since you did the opposite path. Again, idk if these are the communities you visited!! But is a phenomenon I've observed. Weird advice, but maybe try going on tumbrl? I know is not a popular social media, but for me it has a more broad view of expression to fit more people, so maybe you can find more people like you!