I left my insulin at home ‍♂️

[Rokaab]

I remember as a child and going through my teens that if I was hungry (i.e low blood sugar) my mood would change to bad very quickly and I’d be quite shaky but as soon as I ate everything was ok again.

Low blood sugar is not caused by diabetes though since diabetes causes high blood sugar, so if it was low blood sugar it was definitely not diabetes.
I suspect one reason they probably think its T1 because your dad is T1, but they may a done some of the other tests as well.