Hi Sciencelover. I am not sure I can help you with much but what struck me is that your DS had an almost identical SB V to my DD when she was tested at 7. When she was tested the psychologist turned out to be not familiar with giftedness and took three hours to administer the test, so they probably weren't that familiar with the SB V either. We had requested the SB as it has less reliance on timed elements.
DD was comparatively low on working memory, same scores as your son, and knowledge 11 and 14. She also had the same pattern of strengths. I did some research and the working memory is typically 'low' although in the normal range for gifted kids on the SB V. The psychologist can compute the gifted composite score which excludes working memory.
Our DD was retested at 9 with a tester familiar with giftedness and the SB V and the pattern was the same but the scores were much high, except fluid reasoning which she hit the ceiling on first time. Working memory had improved but was still lower than everything else.
I put low knowledge down to the fact that she was under challenged and so knowledge wasn't where her potential indicated it might be if she fully engaged with learning.
Now with DD we are discovering a few different things. She has hypermobility, probable EDS, which makes writing painful. She has always struggled with writing and is having physio for her generally poor muscle strength and joint problems (multiple dislocations in the last few months). The hypermobility is exacerbated by growth spurts and impending puberty.
The second psychologist emphasized that the strong visual spatial/fluid reasoning profile goes with visual learners who can struggle in audio sequential dominant classrooms and they are often unrecognized for their giftedness. This is becoming more obvious in high school. DD is a slow reader, despite reading very early like your DS. She has to turn the words into pictures in her head and that takes time. The reading load is increasing in high school and making life tougher. Her eyes also tire easily due to the EDS and weak eye muscle control.
DD works a lot better on things she is interested in because it all takes a huge amount of effort, it is hard to direct limited energy sources to things you don't care about. However, it is important for us that DD try at all things to learn as much as she can.
DD is very sensitive and if we didn't acknowledge her easy fatigue, need to be fed and watered regularly and make efforts to adapt to her different needs then I can imagine she would have emotional outbursts too. We have been lucky that she has her fathers even temper.
Not sure what else is going on with your son but have a look at visual spatial learners just in case. Linda Silverman is the guru. Lots of info on the Internet. Check her Gifted Development Centre website. Her book is Upside Down Brilliance. We are having DD assessed with an educational specialist experienced in visual spatial learning on Monday.
We are finding that there isn't one simple answer for anything but we are managing most things.
Good luck. Hope you find what you need. Sending support. I totally get the social anxiety bit!