I agree, mine is still in the wait and see stage and like yours the comb got red/big fast. The other one is half the size no signs.Slow feathering isn't always a reliable indication. And hens will also have iridescent feathering - all of my black or black-laced hens and pullets do. The comb is what's making me go, "Hmmmm...." Not sure, though. A couple more weeks and you'll know.
ETA: Fairly certain GLW pullets sometimes have male-looking combs early on. Post pics again in 2 weeks.
I'm still holding out hope on my big girls as the comb has stayed the same and she seems to be growing into it.
Pullets, pullets. Thats my positive vibes being sent to you for your GLW.