Please please please do not worry.
I know this is impossible. You are a mother.
My boy is left-handed and the youngest in his year. He started Reception aged 4 years and 2 weeks. It was a total waste of a year. They put him on 'report' (home/school diary) for his behaviour, he really struggled academically, HATED reading, wouldn't write. ALL BAD.
I was so upset. I was such a swot at school! And he was - and is - demonstrably so bright. How could this be?!
Year 1. His teacher was more laidback and understanding. She saw his behaviour wasn't naughty - he just struggled with the whole sitting still and not chatting thing. He started enjoying school. Still shit at it though. He got extra help with his fine motor skills.
Year 2. Got the best teacher in the WORLD. Told me to stop doing reading books with him, stop trying to practise his spellings with him. He really came on in Year 2. Handwriting absolutely abysmal. Illegible. But the switch started turning on. He got extra help with his phonics.
Year 3 - move to junior school, everything upped a level. The expectations were way higher. He got intensive help with his handwriting and phonics, I started to pay for a maths tutor. He's just finishing the year - he's Expected in Literacy (on the cusp of exceeding), Expected in Science and Emerging in Numeracy. Top marks for effort in everything else - music, Spanish, PE, RE... He gets 10 out of 10 in his spelling test every week. He's on track to meet the bloody government's stupid '100 tricky words' spelling test at the end of Year 4.
He's starting to show his full academic potential after a slow start.
Please don't worry yet, and don't force it. His Year 2 teacher was wonderful, letting us abandon reading books and learning spellings. She knew you can't fill a jar when the lid's still on. My boy is just - JUST! - about starting to read for pleasure, and his reading age is a 9-year old (he's almost 8). He's doing AMAZINGLY. Yours will too.