I've dealt with the clothing issue. That is as a person with autism, allergies, and sensitive skin. My sons issues were a little different and were more linked to patterns or styles of clothing and inflexibility regarding that. My disappointing moment as a little girl was my aunt making me a nice angora sweater. I'd been petting her's getting lost in the feel of it. So here I get this sweater and I develop a rash and it turns out I'm allergic to angora.
Using longer underwear, and undershirts in cotton with soft cotton thread might help some tolerance sometimes. It did for me. I hated seams because they would rub my skin raw. Even as an adult sometimes fruit of the loom cuts my skin. I can tolerate most patterns and colors like anyone. Though I do prefer certain colors. My son is far more flexible now especially if it is a hockey jersy or sports shirt. When he was little there were high pitched screaming tantrums, handflapping, and attempts to get the cloths off if it didn't fit what he tolerated. So I learned to build his tolerance by sometimes slipping stuff over others and after about a week or two totally removing the other item. Its how he was potty trained. He's now 21, living with his dad, working a job, and other than his language issues and sometimes awkward movement he blends in.
Math? I have hyperlexia which is precocious reading ability and learned to read and write before kindergarten. I even wrote professionally for awhile. But I also had dysnomia and aphasia from head injuries. Nothing more irritating but knowing the word you want but being unable to speak it or you can but you can't write it as that escapes you and how it sounds gives no real hint on spelling. I wrote hello in binary on my hands by age of 6 because I was told and read about how computers handshake. I learned to program at a very young age and then also gave that up. My grandfather was technical and was working on a few projects for things. I understood complex math easier than basic math. Once I took manipulatives to see times and division I was fine. I saw algebra simply as a puzzle. I similarly took up an interest in physics and knew the theory of relativity by grade 2. Later I was hurt in two car accidents, and badly beaten by a very bad person who was one of our sports coaches. So I had moments were I was recovering from significant trauma.(such as I'm walking around and no longer in a wheelchair and I am no longer legally blind).
Weather people have a blatantly tangible gift. Somethings can't be counted in science or writing. My son had a kind heart at a young age. He'd pick flowers for bus drivers and try to kiss little girls on their hands(even when he could barely talk to them). It was very cute. He was the first to share, first to offer a hug or bit of concern if someone got hurt. He has slow learner IQ yet he was visual and watched me. Which means he learned to reboot the computer between DOS, Windows, and Linux to get at programs(some games) he wanted to get at. He could recognize things on a keyboard and he learned to use the apple computer at school easily(age 3).
Circle of friends was sort of used at his school. I didn't have that as a kid but I did have the Lions Club. Some of the kids sometimes come from having a family member with some disability. The label is important for somethings but not necisarily for this. They just have to know your kids personality, what he likes, what he doesn't like, his personal boundries. My own parents weren't the best examples of social behavior. I was raised with two kids with antisocial disorder and narcisissm. That proved harsh for me and I went in foster care at least once because of it. I learned about why people react or do what they do from TV and movies. So think about that and what they watch. I watched most old black and white movies, variety shows, game shows(trivia), and other things. At one point when small since real people were used I was confused as to if things were real or not. My grandpa was an actor and had friends that were. So I asked Sabastian Cabot and Brian French when they were camping about their fictional family. They looked at me and then eachother and finally one of them spoke. They told me even though they were real people the show Family Affair was not it was all pretend. I accepted that but for a little while my relatives had to put up with me asking if a show was real or pretend. Some shows I knew were pretend because I'd seen them filmed. Its pretty clear that cartoons and puppets aren't real.
Re one other post. I knew I was autistic around 2 years old or maybe 3. Everyone kept using the word. Well actually they said Kanner's Syndrome. So some had to tell me "you don't introduce yourself then tell them you have that!" I commented back "But you do it." Then they learned to not behave like that. Sometimes non autistics don't realize how they behave anymore than an autistic. My son knew he was different before the age of 3 as well. Its hard to miss when you deal with speech therapists, occupational therapists, and physical therapists. We know we are different from others for somethings even if we don't always know why. I can understand telling a kid they can't behave bad and blame their diagnosis. I used that exact same thing on my daughter who died from brain cancer. They are kids and they have good and bad days. But they know you feel bad about somethings sometimes and they'll try to get away with something or get something. Really they can turn into brats and tantrum too. She had no autism or ADHD but she did develop learning disability for damage to her occipital lobe and ataxia affecting her movement(cerebeller damage). But like her brother she just wanted to be a kid, play with her cat, play on the computer, do crafts, and be silly.