fatbetty. My DS (7mo) is visually impaired. Was DD checked out carefully by a paediatrician inthe hospital, and at the 6 week check? There are a few things they might be able to see during those checks, or is there anything odd about her eyes, like clouding or a strange shape to any part of them?
Some babies really are slower to get into using visual information, and that's probably what's going on, and her eyesight's fine. Some shut their eyes as they just find it too much at first, others seem better at just ignoring it - so I would guess that's what's going on.
You need to trust your feelings though, and I would insist on a referral to a paediatric opthalmologist (or if there isn't one you can see soon enough, an opthalmologist). There are some conditions they might just have missed and, in the cases of the ones that are treatable, they need to be treated as quickly as possible as it's not just the eyes that need to work for a child to see. The optic nerve and the parts of the brain responsible for processing visual information need stimulation in the first few weeks and months of life or they just won't develop properly later. Also the sooner you are aware of a VI, the more you can do to help stimulate a child's vision, understand more about how to help tham or help them to adapt, and it really makes a difference.
At your DD's age they can only look into her eyes and see if anything looks wrong and run things like blood tests which might point to other conditions.
They wouldn't be able to actually test her eyesight until she's a few months old and able to sit on a knee and choose which direction she looks in - they do a test called 'preferential looking' with babies where they look at a plain grey circle and a stripy circle on a flashcard. The baby automatically looks at the stipes as they're more interesting and the stripes get closer together as each card gets more difficult.
There are also conditions that they wouldn't be able to detect without testing her vision, but the things you are doing to stimulate her vision are the right ones anyway.
DS's condition was obvious at birth, and his problems are more with distance vision, so my experience is diferent to yours. I think your DD sounds like she's probably perfectly OK, but it would be well worth getting your DD checked out just because of all the advantages of knowing about a VI sooner rather than later.