Hope you dont mind me adding my thoughts. My 15 DS1 was dx very young with ADHD. He was not yet two.
He slept very well at night because he was so tired. He didnt sleep in the day at all from around 7 mths.
No impulse control so very hard to take him to the park etc. He would simply walk OFF the slide so a bit stressful.
He LOVED telly and would stare for hours if I let him. Only time he was quiet.
Early riser.
Clever but appeared to be deaf (he isnt).
When I took him to playgroups it was alway him that caused havoc. If things were a bit slow he would create a bit of excitment. This meant pushing someone over, spitting etc.
Turned lights on and off, taps ditto, obsessive about certain subjects, why why why why ALL day!
When very hyper he got that glazed look in his eyes.
I would often hear 'my boys just like that' but then they would watch him for an hour and change their mind LOL.
I used to dress him in orange, yellow etc so I could always see him.
TBH its really hard to tell at the age you LO is. I would keep an eye on him and if you are still worried in 6 mths explore a bit further. Its hard to get anyone interested at that age anyway.
My DS is pretty ok now. The ADHD is still there but its not so physical. We found it all a lot easier to deal with when we moved from a little flat with no outside to a house where he could play out.
He drives me nuts but he is a good lad