Is she is reception or year 1?
One of my DD’s started to struggle noticeably (well, noticeably to me anyway, school said she was fine) when they moved to year 1, and it was all around literacy lessons that she lost her confidence and got stressed. She felt like she wasn’t good enough at it and I couldn’t get any concentration from her at home for reading or writing at all (she loved art and crafts and could concentrate easily there).
She is very bright and she was lively and happy and sociable. Okay, I knew she was on the sensitive side and she always had sleep problems and some tantrums at home, but I didn’t have any real worries at that point.
The jump to year 2 made things worse. The literacy work seemed to bother her much so that it began to cause her to cry sometimes before school. School said she was doing well & she did keep up and concentrate in school (no-one was seeing her distress about it, which she showed at home).
If I tried to do any homework with her, we got a couple of lines completed (at most) and then she would be off cartwheeling around the garden before she would reengage at all, then repeat.
To cut a very long story short, she was diagnosed with autism at 8 and ADHD at 9. Still bright and lively and fun, but now on adhd medication (which has helped hugely) and currently on a part-time timetable at school.
It is SO hard for her to concentrate on an academic work that involves sitting down; she needs to move in order to concentrate and to regulate herself when she is trying to learn.
This may well not be the case for your daughter. I share it though as I absolutely kicked myself for not getting my DD on the assessment pathway at 6, as I knew full well that something was going on, but I didn’t trust my gut. It takes around 2 years, or more, to be assessed by the NHS in my area.
By the time my DD was diagnosed, at 8, she was actually fast tracked a bit as she was so burnt out from trying to cope in school that she had become severely mentally unwell she could barely leave her room at times never mind attend school.
She is still wonderful, and has recovered from burnout at the moment, and being neurodivergent is not a bad thing - it is part of her personality and brings strengths too (she has extremely high empathy levels for example, has strong morals, and cares very deeply about people, animals and the environment).
I just wish I had acted sooner because of the effects on her mental health, when we didn’t understand the effect that school was having on her, or how much she needed support.
The risks of assessing for adhd, or dyslexia, for example, are pretty low.
The risks of missing it though are much higher. You are right to keep an eye on things.