The gold standard for dyslexia (which is high on the list of diagnostic possibilities) --or really for any reading difficulty, whether strictly diagnosed as a disability -- is structured phonological processing and phonics instruction, usually in the form of Orton-Gillingham-type reading instruction. School- and clinic-based intervention usually consists of classic OG or Wilson tutoring. You can also pay for Barton tutoring, or use an open-and-go home-based tutoring curriculum, such as Barton (slightly more training required), All About Reading/All About Spelling, or Logic of English, all of which are OG-based. The least expensive options are AAR/AAS and LoE, with AAR having the edge in its terminal level of instruction (seven levels, ending at high school reading level, vs LoE ending at the intermediate grades), and in decoupling reading and spelling, and LoE having the edge in total package price (and being an all-in-one language arts curriculum--whether this is a pro or con depends on whether reading, spelling, and writing are all at the same level in this particular student).
Critical to the success of any of these programs for a child with yours' profile is repetition and review, as she appears to have some phonics skills, but lacks automaticity applying them, which means that she is likely using a great deal of cognition on the act of decoding, rather than comprehension. If automaticity is an issue, she will probably need many more repetitions to attain fluency than most other children of her age and ability.
