You are lucky that you learned about SPD so early. My son will be 10 in a few months and just recently started OT for the first time. I had not even heard of SPD when my son was 5 and in Kindergarten and apparently his doctors didn't know anything about it either. I spent countless hours on the internet trying to figure out the reason for some of my son's differences. I read about overexcitabilities and my son seemed to have all of those, so I thought maybe that was it.
We live in a small town that my son thinks is so much like "Camazotz" from "A Wrinkle in Time" that he refused to read the rest of the book. He felt very different from his classmates when he went in reading at a 5th grade level and also doing math with negative numbers (an older boy in his musical theater class had told him about negative numbers when he was four and he came up with his own way of doing subtraction using those negative numbers so that he didn't have to borrow. For example, something like 26 - 8 he would say 6 - 8 is a -2 and -2 and 20 is 18. When we told the Kindergarten teacher about this on the first day of school, she looked at us like we were kind of weird. When she found out that he could read very well and he wanted to read reports or a few paragraphs from his science enclyclopedia to go along with his letter of the week show & tell, she let him but she didn't want him to pick out books from outside the Kindergarten book area. She didn't want him to feel "different." I remember she told me that kids at the K age are very accepting of differences but as he got older they might not be. I felt that she was trying to tell me we needed to somehow make him be like the other kids.
The Kindergarten teacher did not tell me when the special ed teacher told her that she noticed red flags for sensory and motor issues. The special ed teacher, who I later met when her son joined my son's theater group, told the teacher she thought he needed to be referred for testing to see if he needed OT. We didn't know about it until a year after we were told by a teacher and the principal that we needed to homeschool. The Kindergarten teacher even thought he should be held back in transitional first grade the next year to work on coloring in the lines and that it didn't matter that he wouldn't learn anything because he was already so advanced. We talked to someone in our State Dept. of Education's gifted coordinators office about this and we were told that there was no requirement for OT to be provided unless a child is failing and my son who was reading at a 5th grade level and doing some multiplication was definitely not failing, so he would not have been eligible for OT anyway.
My son also liked mazes and he would sometimes do online puzzles without a problem, but 3D puzzles were difficult for him because of his fine motor issues so he never did them. This is one of the things the OT said to work on. My son is not that good at 3D puzzles even on a good day. He is still slow at manipulating the puzzle pieces. I don't think my son is any less gifted than his highly gifted half-brother, who does not have a sensory or motor issues, just because he can't do 3D puzzles quickly. I wonder if he is even more gifted to be able to do the things he did in spite of his disability. My son is gifted in all the areas where is really counts. His inability to manipulate puzzle pieces quickly has not had any effect on academics that I can see, so I don't understand at all why this would be used to identify giftedness. But I'm not an expert. I'm just a homeschool mom with only a two year accounting degree doing my best to educate my "different" child who learns very differently from me. I never knew there was more than one way to solve math problems until my son came up with his own ways of doing things.
Many times my son has made me question my own intelligence and even my adult daughter had the same reaction recently. But I can do puzzles! Am I really smarter than he is because I can do 3D puzzles better than he can? I know that I am not as smart as he is and any gifted expert who would say that I am because of my ability with 3D puzzles is mistaken. I did not start reading at 2 without being taught or come up with different ways of doing math and I certainly didn't have the advanced vocabulary and comprehension that he does.
My son has never had an IQ test. All he had was the WIAT a few years ago and based on his WIAT scores the educational psychologist testing him told us what he thought he would probably score on an IQ test. He said my son would have to be tested over more than one day to get an accurate score because of some of his issues. I think my son could take two similar tests on two different days and get very different results, especially if he is not feeling well or is anxious about something. One example of this was a test that involved visual memory and my son scored below average on this which was very unusual--he tested high on this before. At home, I had him read some difficult to spell words from a medical reference book and without warning I put my hand over the words and asked him to spell them. He either spelled them correctly or was off by just one letter. There is absolutely no way a kid that recently memorized the spelling of thousands of words for a spelling bee and was able to spell even harder words after seeing them once has a problem with visual memory, yet on this piece of paper it looks like he has a problem. This is one reason I have put off having his IQ tested. I am hoping that sensory integration therapy will help with some of these issues.
My son had vision therapy a few years ago also, and even the piano teacher noticed the difference, but his OT still wonders if he still has some vision issues. In fact, she mentioned something about the "Where's Waldo" at our last OT visit. But the strange thing is sometimes he is good at finding hidden pictures and he used to enjoy doing this--at home. Very, very confusing!
I wish I could be of more help, but as you can see I am still a little confused about all of this myself and I am still trying to find answers.