Feelingsad:
Oh boy have I been there and I know this isn't a great help but time and steady improvement with your child's school work will heal many a wound.
I've posted endlessly here - especially about poor maths curriculum and Halloween-gate (teacher told 8 year old children they're going to hell if they trick or treat). These are just the tip of a very long list of worries/ concerns/ angers toward St. Mediocre.
My feeling is that moving school means you don't have to deal with them anymore - and a parent who's not getting on well with a school/ doesn't trust them is never a good situation for the parent or the school.
Going forward give yourself little projects. If your DS is struggling in an area - reading or maths - help there. If you DS is doing great school-wise but doesn't have many friends yet, get him signed up for clubs next school year (sometimes sheets come round now/ sometimes first week(s) of school).
Give yourself time to be angry and in fact to grieve, becuase part of this is parental expectation -- you had high hopes and imagined going to primary school would be a wonderful experience and in fact your 'vision' of what school should be like has died.
Use the cynicism as a strength. I'm unremittingly critical of teachers who shirk responsibilities, who prevaricate, who are economical with the truth, who cannot communicate clearly what the objective is, who cannot simply inform me how my child is doing and what I can do to help with the next learning targets for my child.....
I know that parents at my old school say that they've had to get active because I'm not there to stand up at 'curriculum meaning' - 'inspire' workshops - class meetings to ask those hard questions. One friend said that a teacher's comment was 'I thought Mrs. PSBD had left our community?' I just laughed and told my friend 'You learn well, young jedi!'
Schools need to be held to account by parents - not just governors (usually hand-picked/ friends/ like-minded teachers in my experience locally) or OFSTED (who can only make a whirlwind visit and may have other agendas - i.e. let's fail these otherwise good schools and force them to become academies - never mind that families will move out of the area, enrollment will drop for a few years).
Embrace your roll as an unimpressed parent. Be that advocate for every child in the school who is their to learn and deserves teachers who are dedicated to making that happen - not just ticking boxes/ writing novels of end of Year Reports which are virtually identical for children in that ability level (just replace name).
Finally use your anger constructively - do what you can to help your child if they're behind where they should be. Encourage their interests and I sincerely believe in encouraging them to do more than just enough. I really feel strongly that this 'just do the minimum' culture sets in at primary and its terribly damaging going forward.
You will get through this and trust me you will laugh about it later.