8 months is irrelevant with Speckles
The age is still somewhat relevant.
If the bird were only 2 months old, I would think it's male.
If the bird were 2 years old, I would assume it was completely mature and would remain a mystery forever.
At 8 months, most males are obvious, and most females are laying eggs. But some males and some females are still confusing at that age, and become more clear later. So there is still a reasonable chance that Speckles may show their gender more clearly with time.
you have no idea how genetically strange this thing is. It makes the strangest noises, does the strangest things, and is so cowardly.
If Speckles is so cowardly, and has been so much picked on by the others, it might not be getting enough to eat. Lack of food could cause is to be weak, act cowardly, get picked on more, and not mature sexually.
If Speckles does get picked on, you may want to consider providing a separate pen for it to live next to the others, where it can eat and drink and do chicken things in peace. A few months of unlimited access to normal chicken food (chick starter or grower or flock raiser or something similar) might make a big difference to how obvious the gender is, and how healthy the chicken is. A wire dog crate inside the main chicken pen might be a possibility.
Here is one article about someone helping a chicken who had been bullied:
https://www.backyardchickens.com/articles/chicken-bully-chicken-victim-a-two-sided-issue.73923/