don't get too worried, main things are patience, love, reading with him and listening to him. And I think you do all those things.
My son moved school in year 1 (and country) his SATs were "unmeasurable" (as he could not write). He was assessed as being 1.5-2 years behind where he should be by the end of year 2
He also struggled socially, and emotionally. He got 3 IEPs (social, emotional and academic) and was tested as dyslexic by age 8.
I remember panicking and thinking about tutors, we did Kip McGrath for a year.
But ultimately, the best advice I had was to:
1.) read with him and to him
2.) be patient with him, don't show my frustration
3.) focus on what he IS good at. In his case he loved making things, so I forked out for all kinds of creative stuff like lego-animation courses (practically free, run by council in a museum over the summer, great fun) and robotics (pricey but worth it) and he used to modify old nerf guns and took apart and re-built radios.
Giving him praise for what he was naturally good at (making stuff, being creative, technical) and not just getting bogged down by spellings (scored 0-2 out of 10 weekly) and times tables (could not do rote learning).
He is 16 now and has blossomed in Secondary, is predicted 7s for most subjects, I (and school) allowed him to choose coursework subjects rather than sticking to ebac, he has very much enjoyed his computing, food tech, design and tech gcses
I wish I'd known, then I would not have worried so much.
Some kids are just not "school ready" until much older. Mine was 10 when he started to focus a bit. Seriously, run with what he loves.
Keep the faith!