Why did those people tell you different? What exactly is the reason for doubt?
If you're relying on feather sexing then there is no doubt it's a pullet. I don't go by feathers unless strain of bird has proven to be sexed that way. The glimpse of dainty leg in first photo indicates pullet...
Leg size and stance will be your best indicator. If you purchased these as pullets from a local feed store then you're nearly guaranteed it's a pullet. Vent sexing at hatcheries is extremely accurate. If you ordered direct from a hatchery and they added "warmth" extras then you're certain it is...