Anna, stop worrying lol.
Roo is female!
I’m absolutely positive.
If she were male the comb would be large and pink like the photo of that cockerel.
Males mature much faster.
The comb starts getting bigger and pink at two weeks.
Because Roo’s comb is still yellow at 6 weeks it’s a dead giveaway that she’s female.
I don’t think any breed that has a straight comb is hard to sex at all.
It’s only difficult when you don’t have chicks of both sexes to compare to.
I have raised six cockerels, alongside pullets, from day old chicks now and they were all straight combed breeds except for Silkie.
I could tell they were male by 2 weeks old.
Silkies are very difficult to sex and I didn’t know until he was about 5 months old.
I’m telling you Roo is a pullet.
Trust me!