Am I doing something wrong?

I just had a closer look on my computer at home. The duck is a bit soft in focus, and I think ISO 6400 is really making a fair bit of noise in your image.

f6.3 is an aperture that would normally give greater depth of field. If you can get your aperture to below 4, and ISO to less than 1600, it will be better all round, and you will get the background blur you want.

There is no substitute for experimentation with your own gear.

I am about to be out of touch for a few weeks, so I may not be able to respond directly, but I will try to help if I can.

Great to communicate with you!

IainD