It sounds like she is progressing, just taking a bit more time. My two older children did not start reading with ease, enjoying reading, until about 1/2 way through 2nd grade and closer to 8. They could read simple things, but when I say reading with ease I mean reading smoothly and with out having to think hard about it.
I know it is hard when you hear what other children are doing, but the more moms I talk to the more I hear about children in similar situations, reading closer to 8 or even 9, we just don’t tend to talk about it as much because it feels like they are behind (even when we know they are progressing). I know a family and the mom was telling me about what her DD was reading, a very difficult book in 2nd grade. I asked if she could read it out loud, was she reading every word, and a couple weeks later the mom told me that when she asked her DD to read it out loud she could not read it well at all. When reading to herself she was skipping hard words but getting the “gist” of the story so her mom thought she was reading it all. Not that some 2nd graders can’t read difficult books, just that sometimes we can hear from parents what they children are reading but to remember that it isn’t always what it seems. Reading out loud is different than reading to self, it takes a different process of seeing the word, reading it and then saying it out loud.
I am currently doing DR level 2 with my 6-year old. I think your DD would find it repetitive because Level 2 is word building. He is learning to build words one at a time, and it sounds like your DD is able to read individual words, it is just working on reading with ease and smoothly when the page is full of words.
I found that pathway readers progressed really fast from simple to more challenging. For 1st grade and early reading I preferred Rod and Staff Bible Readers (shorter chapters and slower to progress in difficulty) as well as simple readers like Dick and Jane books. I would find easier to read books for your DD to practice with and help build confidence back up. Also 15 minutes of reading, when it is not yet “easier” for her would get tiring, 5 minutes when still working on reading can often be a good amount of time. If you want to go with 15 minutes, take turns reading a page with her. You read a page and then she can read a page that way it is not as over whelming.
I also found that when moving into books with more words on the page what helped my kids focus and not get overwhelmed was to use a ruler, or anything with a straight edge (even a piece of paper) and block all the text under the line they were reading. That way they only have to look at that line, and as they move down the page it helps them not reread the same line over and over on accident.
Take your time, it sounds like reading is coming along, maybe just not as quickly as you had expected. It amazed me how my children went from struggling along to almost over night they were reading with ease and now they won’t put books down, but it was hard going into 2nd grade and they were still working on enjoying reading and reading smoothly and with ease. I would find some simple books to help build confidence, and just have around the house for her to pick up and read in her free time, as she continues to practice and not have the lessons get too long.