Hi Tinkerfell:
First of all I think you should have a read through the Mumsnet learning pages on progressing through the NC Levels in primary school here: www.mumsnet.com/learning/assessment/progress-through-national-curriculum-levels
I think this will reassure you that your DD's progress is quite typical. Also please bear in mind that progress is in spurts at this age - they just suddenly get it. They may struggle for a bit with sounding out longer words or adding/ subtracting numbers over 30 and then suddenly they're fine. It's not always obvious why - it just makes sense to them suddenly.
Perhaps I'm wrong - but I think some of the sub-text of your comment is a distrust that the school is doing all it should be doing with your DD. A very good 'reality' check on what is possible to teach children in an ideal world is the primary curriculum prepared by Campaign for Real Education: www.cre.org.uk/primary_contents.html
This is presented by area of the curriculum but gives you a very clear idea of what should be covered in a given school year. I stress this is 'ideal' world stuff and your school may well not be teaching to this - but it does demonstrate what is possible 'in an ideal world'.
Finally, as someone who has posted here over the years with sometimes extreme frustration at aspects of the curriculum for my DDs (now Y3 and Y5) - one thing to bear in mind is that you can't control how or what the school choses to cover with your DD but you can enhance what they learn at home. There are all sorts of fantastic resources on-line. Some examples are:
Mumsnet Learning learn at home zone: www.mumsnet.com/learning/learning-zone/learning-zone-introduction
Oxford Owl (Reading): www.oxfordowl.co.uk/Reading/
Oxford Owl (Maths): www.oxfordowl.co.uk/Maths/
BBC Learning [BETA] teachers pages of KS1: www.bbc.co.uk/schools/teachers/ - just click the KS1 tab at centre left in orange outline box - and then select appropriate area of the curriculum
BBC KS1 BITESIZE (revisiong for Y2 SATs): www.bbc.co.uk/bitesize/ks1/
crickweb (KS1 resources): www.crickweb.co.uk/ks1literacy.html - just select KS1 on blue menu bar and scroll down to appropriate subject. Lots of on-line games to support learning.
Woodland Junior School Maths Zone: resources.woodlands-junior.kent.sch.uk/maths/
Woodlands Junior School Literacy Zone: resources.woodlands-junior.kent.sch.uk/literacy/index.htm
Woodlands Junior School Science Zone: resources.woodlands-junior.kent.sch.uk/revision/Science/index.html
and there is nothing better than getting your DD reading as much as she can. Join a library, swap books with friends, visit charity book shops/ stalls, etc...
HTH