A lot of them can look a bit like they could use a comb over when they ball up. While their quills are dense the diameter of them make it impossible to be thick like a dog or cats fur. So it may not be really thinning at all. A picture will give you the benefit of fresh eyes on it. But the fact that she is losing full normal quills is actually a good sign.
During any of this time did you do a diet or being change or change bathing products on her?