If your daughter is working towards then the school should have offered intervention classes .. I think the most important being reading because if they cannot read fluently to the expected level then that could have a knock on effect with reading questions for other subjects.
I would ask your daughter if she wanted tutoring as she may not want it.
I would do a little with her at home to boost her confidence. Spellings are on the national curriculum and the maths requirements. For English you could Google writing mats for the year she is in and work on those with her and repeating it all. It is all about learning thought repetition so the more practice she does the better. It will boost her confidence.
Ask your teacher firstly whether the school provides intervention classes for children working towards. If they do then that's great use them.
My sons are shy, they are loud in every other situation other than school but they are working at greater depth for reading but still shy to talk to teachers.
I was shy and I think confidence can come with age for some children. Yes helping them learn helps boost their confidence too. It is tricky because hard to know why they are shy in certain circumstances.
In terms of helping her at home I find Year related CGP books are good for reading and one for spelling punctuation and grammar are good as well as maths.
Also Schofield & Sims first mental arithmetic exercise books are great and are for KS1. She will probably need to start on 'First Mental Arithmetic 3 and 4 and carry on until 5 before moving to Mental Arithmetic introduction and from 1 to 6 which are for KS2.
So if she has started year two also use KS1 SATS papers for:
• arthmetic
• reasoning
• reading
• spelling
• grammar and punctuation
They are all available online for free. Luckily she will not have to do the sats exam this year because last May was the last KS1 SATS papers and they are no longer compulsory.
I have used all of the above on my eldest son and he is doing well scoring greater depth at the exams. I think by helping them at home it helps with their confidence during classes and makes them less shy to speak up in class, obviously that may come within time but the have improved over the years since reception. They are now in year 2 and year 3 and have become more confident but still more help required to boost their confidence.
I hope the above helps and your daughter gets to expected. You do worry for them. She will be fine.