While there are many definitions of dyslexia, most define it as a difficulty with breaking of the code of reading - the sound symbol relationship, phonemic awareness, sounding out and "reading" words. Here is what the International dyslexia association says:

Dyslexia is a specific learning disability that is neurological in origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede the growth of vocabulary and background knowledge.

It is very common for bright kids to have strong comprehension skills, yet be unable (or inefficient) at looking at a group of letters and recognizing what it says. My son is much your daughter - he tests in the above average to superior range in measures of verbal intelligence and speech and language processing, and listening comprehension. Yet, has great difficulty (in the lower 15 percentile, reading lists of words and reading passages accurately and efficiently. Because his decoding skills are so poor, his overall reading comprehension suffers. Yet, he is able to comprehend and remember information presented orally.

If you want to test for dyslexia, you need to assess in areas of phonemic awareness, rapid naming skills, spelling skills, word reading skills. Here is a link that lists and describes some of the tests that assess these areas: http://www.concordspedpac.org/Whichtest.htm

Also - here is a quick list of warning signs for dyslexia: http://www.interdys.org/ewebeditpro5/upload/Is_My_Child_Dyslexic_9-12--8.pdf