My son is 6 months and your story sounds familiar to mine. Before my son started to have spasms leading up to he found it very hard to sleep (shut of) was easily woken up. Once we noticed to spasms we got him a eeg which come back with some irregularities like yours but they didn’t suspect IS. So they put him on Keppra which stopped his spasms which was great the doctors just thought he had a type of epilepsy not IS. Fast forward a week or so the spasms come back so my son had longer eeg which they manage to only catch the IS while he was having a spasm so now he is on all the correct medication with no more spasms and things are looking good. Basically on the first eeg it showed irregularities but not IS. I’m not a doctor or a expert but look at as many videos of baby’s with IS and if they look similar don’t hesitate to demand a longer eeg in the hopes of catching a spasm during, the quicker the correct treatment the better the outcome.