sciencelover, please don't worry about posting here - you are most absolutely welcome to post!
My son recently had a private psychological evaluation because I suspected ADHD along with being gifted. The testing confirmed both these
Can you tell us what made you suspect ADHD? There are a few of us here who's children have been incorrectly diagnosed with ADHD when it was actually an LD (or something else) that was the true challenge. I'm not suggesting your ds doesn't have ADHD, just curious about the reasons you suspected it. There can be quite an overlap in symptoms between different diagnoses.
(although FSIQ was quite a bit lower than I would have guessed).
I am not familiar enough with the SB to comment on the scores, but fwiw, I suspect that if your ds had been administered the WISC, he would have received a GAI calculation that was higher than his FSIQ. The GAI on the WISC removes the processing speed and working memory subtests, and it appears that working memory was a significant dip in scores for your ds. I'm not sure how processing speed impacts any of the SB scores - but you'd see the impact in timed tests.
I'd also add that an FSIQ of 130 is a high FSIQ

He has huge issues with writing--not so much handwriting, but coming up with what to write. So far the testing psychologist along with a developmental pediatrician have said that it's probably because of the ADHD. However, I was wondering if it could be a learning disability.
My ds13 is dysgraphic and also has an expressive language disorder that impacts writing. He had a diagnosis of "Disorder of Written Expression" when he was first diagnosed with dysgraphia in 2nd grade. We didn't realize until he was around 9-10 years old and his dysgraphia had been accommodated that he was also struggling to get thoughts out. The first signs of this were in classroom writing assignments - he often had no idea of what to come up with to write about. Open-ended assignments are the most challenging for him.
Last year (before this psych evaluation) I asked the school about evaluating him but they really didn't want to and basically said "we legally have to if you request it, but let's try these informal accommodations first".
My personal advice would be to get a private SLP eval. You can request the eval from the school, but it's been my experience that we have received much more thorough advice and information through private evals. In our case, our ds would never have qualified for school district SLP therapy either, because ther is a very specific set of bars which must be met to qualify, and they include speech issues which he doesn't have. His scores were on the speech eval were also too high to qualify across the board, yet they absolutely showed large discrepancies in ability and revealed the expressive language challenge. He's been working with a private SLP for 2+ years now, and it is absolutely the single best thing we've ever done for him with re to writing.
The informal accommodations worked sometimes, but not always
Can you look at any of his past writing and see which types of assignments he was successful at and which were really difficult? I wonder if the inconsistencies you saw were related to getting help or if they might have been related to the type of writing assignment. Some things are absolutely easier for our ds to write about - things that are factual or things he's observed.
and they weren't consistent in implementing them.
This was always a challenge for us in our ds' original school. It's also very teacher-dependent. It's one reason that getting an evaluation and either a 504 plan or an IEP is *very* helpful for 2e students (or any student with a challenge) - it gives you a formal document outlining what support needs to be provided, and when it's not provided, you point out to the teacher/school staff/etc that it's required.
That said, I've also found that parenting a 2e child through school requires a lot of extra attention on my part, keeping up with what's happening, and supporting my ds with extra help/tutoring/etc outside of school. The help that the school could and would give wasn't enough to really help him in the way he needed it.
On his last two report cards he got "at grade level" for writing, only because the teacher sent the graded papers (they don't all count for a grade) home and I sat with him for hours pulling every single word out of him.
I'd suggest you need to do two things - one is to seek outside testing, but the other is to put in a formal request for an evaluation through the school. You need to let them know the type of support and how often/much you are providing at home - it should most definitely be included in the evaluation.
The other thing you wrote sounds so familiar - "pulling every single word out of him". This is not typical. It's a sign of a challenge, and it sounds soooo so very much like my ds.
could anyone give me any ideas of how schools can accommodate for weaknesses while also challenging him?
The first step toward this is to really understand what's going on with his writing challenge, hence I'd seek out the additional testing through an SLP. I'd also wonder if what you're seeing is ADHD or something else that looks like ADHD, and I think that's important to tease out before you can come up with a good accommodation plan. What did the psych who did the testing at 7 years old say about the NEPSY results? What did he/she have to say about the ADHD diagnosis - what testing/behavior surveys/etc was taken into consideration to come up with it?
Likewise, it's really important to have him placed appropriately for his intellectual level - even if he's struggling with writing. When my ds has been successful with writing at school, he is *very very* good, and it's clear that he needs to be writing at his intellectual level, not at a lower level. My ds also became very discouraged in elementary school because the pace of classroom discussions and work was below what he was capable of, but the school wouldn't advance him because of his writing challenge.
Last year at age 7 he had an OT evaluation where he was given the Beery VMI and his results were (score, percentile):
Visual Perception 142, 99.4
Visual Motor Integration 99, 47
Motor Coordination 97, 42
That's a really large discrepancy in scores - did the psych have an explanation for it? You see discrepancies like this in kids with dysgraphia - have you seen any potential dysgraphic symptoms? Did your ds' NEPSY tests (or other psych tests) include anything called "finger tapping"?
Your ds also had a low score (not just relatively low) on "word generation semantic" on the NEPSY - this is the type of skill my ds had a lot of difficulty with when he was first diagnosed with an expressive language disorder.
Sorry this was such a long reply - I hope some of it helps!
Please feel free to ask us more questions

Best wishes,
polarbear