Wow. This forum is a lifesaver. Thank you all for responding/following/listening/sharing good resources (love the book suggestions).

My son turned 3 a few weeks ago. I am a former Special Education Teacher and I have a lot of experience with children who have been diagnosed with emotional and behavioral challenges. So, I have been using the techniques I used for years in the classroom and to help parents and as we approached age 3, I came to the conclusion that I need help, so I asked my pediatrician what to do and she referred us to the psychiatrist. She is also referring us for an OT eval.

Here is our backstory:
Our son was colicky, never slept well until about two and still has great difficulty falling asleep. He communicated/spoke/recognized letters/read early. His gross motor was either average or just at the end of the normal expected range.

He seemed to choke on food easy, didn't latch well at the beginning of breastfeeding but otherwise no other feeding issues.

His physical development is consistent, he is very large for his age, always 99 percentile or so in height, physically healthy aside from a bizarre severe allergy to dogs, which confounds the doctors (and breaks our hearts).

Currently, he has probably 5 of 7 days a week in which he has tantrums up to 15 times a day and the duration of at least one can be up to two hours. He has always had difficulty with transitions. He is driven to finish tasks before we move on, if he sees a cabinet door open and we leaving the house, for example, he can't leave until he closes it. If he is enjoying a song in the car, he screams for us to not turn off the car until the song ends. He loves routine, he struggles when our schedule is off. Order is important to him, he enjoys cleaning his room and taking inventory of his books, toys, etc.

I thought he might have ASD at around 18 months because he was only interested in letters and puzzles (for several consecutive hours). He was always very social and was speaking in sentences and had a vocab of about 100 words at the time so the doctor was sure it was not ASD.

It was around 2.5 when someone with a gifted son approached me and said that her son was so much like mine at that age and she thinks he's gifted. I checked out a book at the library/researched the topic online and it was beginning to be clear. But I definitely had a denial/shock phase. The psychiatrist said that he is clearly gifted but I still have those moments when it hits me in the gut (all of the anxiety about his future)and I think, "Maybe we are all wrong?" Many of my friends are teachers in the lower grades and they sometimes give me scary looks and say things like, "I have kids in the first grade who can't do that [insert something academic]."

When the psychiatrist asked about sensory issues, I listed a few things but when I got home, I began to remember: he screamed at every single diaper change until about a year, wasn't into being snuggled, one of his first words was "light" and he obsessed with lights for a year, he always, always, always resists a bath, screamed at every toothbrushing until recently, hates his hair being combed, tells me that he hates certain shirts. One of his first big sentences was, "I want a different shirt". This is all evidence pointing toward SPD.

We aren't sure if he knows what to say to get out of something like getting his hair brushed so that he can continue doing something he wants to do or if he is bothered by his hair getting brushed. It's so hard to know because he is very emotionally intelligent and uses certain phrases to get out of other things. This is where the question of this behavior being an overexcitibility or SPD.

The preschool teacher has never seen a tantrum or any sensory issues. Really, we only see these issues at home.

Tonight we went to a birthday party at a bouncy house venue. The last time we went, a year ago, he would not get into the bouncy houses and only wanted me to tell him how the pumps worked. Tonight's party was a evening one with black lights and music, we were very curious how it would play out. He thought it was great, ran around playing. When it was pizza time, everyone was sitting in a room eating and watching the birthday boy open presents. He jolted out the door down the hallway. I went after him and asked him what he was doing, he said, "I hear someone crying, I need to see if they are ok." He kept running down all of these hallways and at the very end was a toddler crying with her mom. They were so far away and no one else heard her cry. I have no idea what to make of that. Sensitive hearing? Genuine concern? Jolting from the frenzy of the party, hearing a cry and happy to find an excuse to jolt?

Thank you all again.