An option often recommended for puppies is to feed 4-6% of their current bodyweight until they are mature, then switch to 2-3% of their ideal adult weight. So if you're able to weigh Winnie regularly (if your vet is nearby you could pop in and get her weighed there) you could try that for now. But I wouldn't change to the adult amount until she's at least 12 months old. Even then, if you change and she loses or gains weight you'll have to adjust the amount accordingly. It's really a case of using your judgement about how you think she looks.
I notice in another thread you're thinking of switching her to Skinners because you know somebody whose Cocker is thriving on it. Winnie may thrive on it too, but you'd still have to use your judgement about how much to give her as no 2 dogs are the same and feeding guidelines for any food are just that, guidelines.
