New - need some reasoning!

Hello, I have just found this website, was just googling information as I cannot find anywhere to discuss, rant, ask for help.

im Julie.   My 30yr old daughter and her two children live with myself and my husband.  We support my daughter whilst she works by working around her so either she or myself are at home for the kiddies, aged;  girl 11yrs 10 month (high achiever at school) and 3yr 8 month boy (he has been in and out of hospital a lot due to his chronic asthma where hospital staff tend to write on their notes  'global development delay'

If you don't mind I will talk about him and his behaviours that, with three adults in the house, can still wear us all down.

from around 1yr old (I will call him Sam though it is not his real name) I thought something not right, he would be glued to cartoons on television to the point I was there but not there, I could wave my hand in front of him and he wouldn't blink only see television not me.  Fussy eater, one minute liked something next minute repulsed by it.

sam was still having food in smoothe form till about 2yr 6month, it was all we could do to get him to eat. He has never been repulsed by chocolate, cake  or sweets though.

sam was walking by 15month.   walking Soon turned to running, jumping from furniture, still fixated by cartoons on television and then he moved onto my iPad where he soon learnt my password and very confident with iPad, screaming outbursts if taken from him.

by 2yr Sams  eating still concerned us, he didn't attempt to speak only scream when asked to do the slightest thing so health visitor did an assessment and referred him to a specialist.  Apparently with the 2yr assessment if a child scores 50 and above is referred for somewhere on the autism spectrum, back then at 2yrs Sam scored 110.  That was November 2015 - still no assessment. 

by 2yr6 month Sam would throw himself at floors, walls, furniture anything next to him if upset or if something is taken off him.  He rarely cried when clearly he was hurt whilst throwing himself at anything - we became complacent, we lived with this daily so it just became Sam having one of his moments.  

sam could recognise numbers if u asked him a number in writing but he didn't say anything including Mummy or Nan till about 3yr3month.

its always been the norm for Sam to have many bruises on his body, we try to distract him a lot when he is about to start but at 3yr 8month whilst his development and behaviour has positively bettered, I find it hard to believe he would score as high  at 110 now as he has come a long way since aged 2yrs however some of his behaviour  is still concerning.

he was finally potty trained by 3yr 3 month,  then we removed potty and bought little boys toilet step and seat but without the potty he just kept wetting himself. He would occasionally use the toilet and clap with us for the effort but If he pooh' he would touch it and then wipe it on furniture and floor.

we have now bought another potty due to the last five months of battling to get Sam to use the toilet  and he has taken to going back on the potty but we can't trust him to be alone doing a pooh because of his behaviour towards it some times.

sam also is extremely resistant, he always has been but at 3yr8month his resistant behaviours are harder because he screams, protests, kicks, throws things at us  just to get him dressed or to get him into the bath. It can be exhaustive.  We have to close the windows sometimes for fear of neighbours wondering what's going on and all that is going on is we are trying to get him dressed or to get in the bath (he loves playing in the bath).

Sam can now say probably 30 different words but sometimes his speech can be quite random acts than him taking part in conversation.  He doesn't interact as well as I would expect.  He can accurately say things he has heard from his love of peppa pig episodes so to an outsider sounds like he has an ok vocabulary but we know he is repeating from tv.  His vocabulary is getting better by the week but I'm not convinced about his perception and understanding, it's just something we have picked up on because we are with him all the time.  Sam also likes licking things, I'm forever saying don't lick that when I find him licking the leather sofa for instance or he has had a lolly pop then licks all up his arms and hands. 

Going out can be such a drama, he screams and shouts from his pushchair if he doesn't want to go in a particular direction like he wants to dictate the direction. I tend to take bags of goodies to do a quick desperate chore because of the stares and comments, to the outside world Sam looks a lovely looking little boy with probably bad parenting.   He is now back on a dummy. I know we shouldn't at 3yr8month but it does help at bedtime because although he was off the dummy six month ago we have gone through a nightmare getting him to stay in bed etc etc,  I now use the dummy as a reward if he lets me dress him or put him in the bath or put him in his car seat, he loves sucking his dummy and it has a calming affect on him that the dummy has prevented a lot of his resistant behaviours so we are reluctant to take it off him again.  My theory is some doctors prescribe medication, we have prescribed a dummy.

Ps. His new nursery place of 3hrs a day say whilst he screamed the place down when we left him there the first month, he has settled well, a happy sociable little boy who likes his own space and playing alone but now happy to play alongside other children but they would like to refer him to speech and language and are concerned about his understandings they too are not convinced he understands well when talking to him.

Can anyone else relate to this?  Thank you for reading.