Hettie:
I think you have to decide what matters for you as a parent.
When DD1 was in late Y2 it really bothered me that my child couldn't add 2 digit numbers or subtract (even 1 from 10). I got the 'she's at expected level' for all subjects on every report card up to late Y2. In fact she wasn't as she scored straight NC L1 for KS1 SATs (obviously Teacher Assessed/ but backed up by testing), which is below nationally expected attainment at end Y2.
So my advice would be not to 'get over yourself' but to determine several things:
What do you expect your child to be capable of doing (this may require a bit of research to determine what is notionally achievable at a given age - but there are some pretty good indications from the new national curriculum programmes of study: www.gov.uk/government/collections/national-curriculum - just scroll down to programmes of study by area of curriculum
or have a look at Campaign for Real Education's primary curriculum statements here: www.cre.org.uk/primary_contents.html -
both are laid out by school year and give you a strong indication of what notionally your child should be covering and preferably mastering at a given age. Campaign for Real Education is more of an 'ideal world' concept - than probably is practiced in most schools - but it does give you the ability to conceive what is possible in ideal circumstances (great teachers, excellent support/ facilities, etc...).
My view is this - at primary age (as you say you are well educated) it is very easy to do more at home or to explore where there may be sticking points (e.g. sounding out longer words, skipping words that are tricky or new, avoiding finding out meaning of words, problems carrying numbers, difficulty remembering times tables, etc...). There are all sorts of stumbling blocks along the way and in reality there is no one way to learn or teach this stuff. Schools get very precious about how you have to follow their system or you'll confuse the poor dears - but they rather forget that sometimes the teacher themselves isn't particularly well trained/ talented in that area of the curriculum and sometimes working quietly at home (maybe using old fashioned methods) can work. Let alone the fact that a lot of well behaved, quiet children just simply get overlooked and slip through the cracks.
I get that dyslexia is a niggle - but don't jump to conclusions yet. However, if your husband is dyslexic as well - then the there is good genetic grounds for that worry (for girls it has to be in both mother & father's family) - but it doesn't necessarily mean it will come to pass. Sometimes it's about just being ready to learn this stuff (and that can be about being able to sit still and concentrate, being able to conceive what someone is describing, being ready to think in more complicated ways, being ready to settle down to work, etc...).
Y2 in the UK = 1st Grade in the US. Many arrive at age 6 unable to read and maybe only able to count out loud in US. Many leave 1st grade still struggling to read and not very good at maths there but go on to do very well indeed - and in fact looking at PISA results I'm not particularly clear that 2 extra years of schooling in the UK is reaping many benefits.
HTH