Irregular fill at curves in Illustrator

Hi!

This is the first time I've had this issue using Illustrator CC and I'm finding it difficult to describe but here goes:

The fill does not match the stroke of my shape (in this case its a letter) here's a screenshot:

Where as when I enlarge the shape (not zoom-in just enlarge), it looks fine -see second screenshot:

I'd like to avoid working on such a larger scale for the fill to work correctly. Any thoughts?

Thanks in advance.

F