Yes there is EVERY chance they are ALL still pullets!Any chance that they are ALL still pullets?
Wanna add this info re ISA Browns. I've had several varieties of red sexlinks, and have found there is no other red sexlink variety quite comparable to a True ISA Brown. Their eggs hit jumbo size within their first year of laying, and their egg color is a rich deep golden brown.
The reason I mention this is because the ISA Brown "formula" is privately owned, proprietary and a closely guarded secret. The only way to get a true ISA Brown is from a hatchery or a store that uses said hatchery. (I buy ISA Brown day-old chicks every other year direct from a hatchery.)
Rhode Island Reds and RIWs are supposedly part of the "formula", but it's not possible to cross a RIR with a RIW and get a true ISA Brown. Don't get me wrong, all the other red sexlink varieties i've had are great too. You will be very happy with your pullets and their egg-laying talents.
I am including a link about ISA Browns for two reasons.
1) In most ways your pullets closely resemble true ISA Browns.
2) The article mentions the copyrighted/protected/proprietary formula of a true ISA Brown.
https://learnpoultry.com/isa-brown-chickens/