My DS3 is August born. He repeated Reception as he was very immature. Unfortunately he has never settled with the new group and he always remained friends with his previous group of friends. He is now in Y3 and all these years very unhappy. Academically he is good but he may have dyslexia and his reading is still coming along. Currently top set at everything.
As he is not at his 'correct' year group all the age standardised tests are from the year above which is not very helpful as he hasn't completed the curriculum of that year.
I am debating with myself on whether to move him a year or not. Although academically I think he is at the correct year group, he really struggles emotionally. I am also afraid that he will be bottom set and that this might have a bad impact too.