The original sentence is:
I don't think the で in ～ないでいると～ indicates て形 but rather I have the feeling that ～ないでいると～ shows two situations that almost occur at the same time.
I would translate the above sentence as:
While still in daze that I could not say/reply anything, Haruhi took a digital camera and said 'Let's take some photos as souvenirs'
or literally as:
While I was in a situation where I could not express my astonishment, (before I could do anything), Haruhi took a digital camera and said "Let's tale some photos as souvenirs."