My son has been diagnosed with moderate SID/SPD and we just finished 5 months of OT. You are lucky to have a diagnosis so early. I didn't figure things out until he started 3 yo ECFE preschool. When he was almost 2yo we had to pull him out of daycare and I started staying at home with him because he was so stressed at daycare. He was hitting and biting other kids everyday and the teachers were out of ideas and so were we after meeting with them every week to discuss it. Now I understand why. With all his sensory processing issues, daycare must have been a torture chamber. He still struggles in some group settings and has a lot of eating issues (texture, smell, etc), but life is getting better. Now that I better understand, I can help him anticipate and deal with many situations. I can also recognize the signs of when things are too much and help him through it. I also recommend reading "The Out-of-Sync Child" and "The Out-of-Sync Child Has Fun".
Feel free to email me privately if you want to chat more about our individual children.