Have you asked any of the professionals what their thoughts are? They may all have assumed that the others have discussed things with you...I've heard of that happening before. I think your first port of call should be one of them, and you should ask them what their thoughts are about the possible diagnosis.
I know what t's like to not know. I was in your position when my DS was around the same age. His 'symptoms' were different, but he was diagnosed with Autistic Spectrum Disorder just before his 6th birthday. That was both a huge relief and a huge blow, in equal measure.
We had lots of professionals involved as well, but we knew that they were looking at an ASD assessment. The Ed Psych got us to fill in a pre-assessment questionnaire at our first meeting, so there was no doubt what they were looking for.
What really upset me was the people around me, and their comments. usually well-meaning, they would try to stop me from talking about his symptoms and behaviours, telling me all children did these things, that it was normal, etc. I knew it wasn't, and it would have been a heck of a sight easier for me to handle the process if people had been willing to let me talk about it, and willing to just listen sympathetically instead of trying to reassure me. I used to think, 'well, if it's normal behaviour, why is it affecting us so much? What's wrong with me/us, that we can't handle a normal child?' I fell out with one person so badly due to her inability to accept what I was saying that I still can't speak to her, three years (of very obvious ASD and high level of need) later.
To be honest, 'it' is obviously 'something', otherwise you wouldn't have all these people involved, and that is what I would say to other people. Children with 'nothing to worry about' don't have professionals crawling all over them. As to 'what' the 'something' might be, that's best left to the professionals involved to discuss with you, which they should do. Ring them in the morning!