If you, her Mum, have a feeling there is something blocking her progress, I'd guess you are probably right.
Dyslexia Action (a charity) will have an ed psych look at her for you (for a fee) and help you forward. They have a website and branches all over the country. I took my daugher to Dr Sue Fowler who runs the Dyslexia Research Trust (also a charitable foundation) at Oxford University, together with Professor Stein. They also have an office in Reading if that is accessible to you. They ask for a voluntary fee but might be able to waive or reduce it.
I did this because I was living overseas at the time and good diagnosticians were not available. Once I had an idea where her learning strengths and weaknesses lay I and the school had more idea how to target help efficiently. The ed psych will provide guidance, whether she has dyslexia or some other difficulty.
Not every school has a dylexia expert (I'd say few do) and it seems to me that it can take a long time to get much done. Too often, the expertise just isn't available. It's not a case of "going private" - you might just need to access expert professional help at this one point in your child's life.
She is still young, of course and has time to develop, especially if she is in the younger half of the year but by the time a child is 7, the way they read tends to be a good indicator of future performance.
Look at the websites of the above charitable institutions and they will tell you that the key to helping your child cope is early intervention. Being behind ones peers is no fun and the earlier you give support, with luck, the less intervention you will need.
I hope I am not out of order suggesting this but sometimes lack of progress is down to one very simple thing. For me, it was important to be doing something, rather than waiting to see how things turned out. I had a long chat on the phone with one of the staff from the Bristol office which alone made me feel much better.