I'm honestly confused by this. You came on here, asking for advice about your duck. Clearly you did that because you can see there is a problem. However, when all these people tell you what the problem is and how to fix it, you just argue and say there is no problem.
If you're not going to take the advice of all these knowledgeable people, even though you sought out the advice in the first place, then why even start the thread? If you insist that you are doing everything right, and she just needs to swim to solve the problem, then why did you even ask about it at all?
I sincerely hope that your duck somehow manages to get better, and live a long and happy life. But, I can tell you that it most likely won't happen unless you make some serious changes, and accept that everything you're doing is not perfect.