I would recommend working with the SENCO at your DS2's school. If they are good, they may be able to get the assessment process going, and organise more help in school. And he may also be able to get some help out of school, e.g. a referral to an occupational therapist, to work with the fine motor skills that he finds difficult.
If you do get him assessed by an educational psychologist, you should get a much better idea of his specific strengths and weaknesses, and some strategies to help. For instance, he might need to have a notebook that you and he uses to write down what he needs to remember. (My son had a homework diary for school, and we wrote in it everything he had to remember in school: things to do, things to bring home etc. Now, at 17, he does that for himself, but knows that he has to write things down to remember them.)
When he is older, if he is assessed as dyspraxic he is likely to be able to use a laptop in school and to get extra time in exams (e.g. 25% extra) and type exams. This may make a big difference to what he can achieve, especially if his handwriting is both untidy and very slow, like my DS's is.
I am writing from my perspective, as the mother of a much older boy, and from my own experience, so I hope that this has some relevance to what you're going through.
I would recommend the Dyspraxia Foundation as a good source of information and support. I believe there are local groups in some areas.
Finally, for my son, his assessment as being dyspraxic was one of the best days of his life! He had spent 12 years knowing that he was a bit different and that there were things that he couldn't do easily that others could. Knowing he had dyspraxia didn't make it go away, but gave it a name and also helped him access a lot more help. It is still hard work, both for him and still for us, but it has probably made him a nicer person that he would otherwise have been.