At what age will a Brittany dog get her adult coat?

We got Milly from the Animal Control, thinking she was full grown. They told us 1-1/2 to 2 yrs of age. Two different vets have told me she was only 6 or 8 months old. At first she didn't shed at all. Now after we've had her 2 months, she seems to be an Olympic level shedding champion. We give her the best food, grooming, baths about every other week, more if she gets muddy. Our entire existence is coated with dog hair. Her new coat seems rougher and not so silky. Was that only baby fur?