My child achieved 2b in his Year 2 SATs and was consistently well below average. At this stage it was also mentioned that he needs language therapy, does not properly understand English etc. I ignored everything.
He then proceeded to achieve a 5a in his year 5 SATS in Maths, writing and spelling, and according to his year 5 report had already finished everything that is going to be taught in MATHs in year 6. He is currently just started doing year 8 Maths in his year 6 class (together with 2 other kinds in his year 6 class, in a small very average state primary comperhensive) and has jumped at the front of everthing in his class (despite being the youngest) including Science, English writing and Spelling. His teacher can never put down a story written by him unless she has read it all. I have also read one or two and it is actually gripping staff! Only compehesion still eludes him; he is "only" well above average in that.
Different kids have different ages at which their mind develops. Count yourself lucky. Your child will flourish at a later age, and hence will burn out much later as well. This comes from a professional with more that 20 years expeirence in HE. By the way, I am a University Professor in Econs and Maths and much the same was said about me when I was your daughter's age.
My daughter achieved level 2b in her recent year 7 sats, and the teacher has told me that she will never pass the 11 plus. Is this correct?