need advice

I currently have my son enrolled in a group program twice a week for 2 hours and speech once a week for 25 minutes.  He is almost 2.

The group program is going well, he adores circle time, has been singing the songs he learns there at home complete with the hand motions, and seems to like all of the activities that they present, but while the transition issues have gotten better, they are still there at times.

The speech also has been going well, though the session is always so short and just zooms by.  He now has about 75 words, mostly nouns, but has started asking for more, to open, and saying verbs for what he is doing - stir, etc.  So I am excited about this progress.

Here is what I need advice about, I am wondering if I should get an ot evaluation done or get more services for him since he seems to enjoy them and they definitely seem to be helping.  We are having major tantrums lately, and while they are always very short in duration, they are intense and seem to be happening all day every day.

I was never told that he has sensory issues, though he was diagnosed as severely autistic at 20 months old.  I don't think he has any clear sensory issues - visual, smell, touch, sound.  But I was reading online that children can have sensory issues that are emotional and related to self-regulation, could he have sensory issues just in this area?  Do other sensory issues seem to pop up later?

As I have mentioned before, I do question the autism diagnosis, but I am currently trying to treat the symptoms and not focus on the diagnosis, but I go back to the diagnosis all the time and question if I am getting him the best help and services possible.  I did turn down aba, but sometimes wonder if I should add that again.  Though it would be hard to fit in with the other therapies.

He also has not been great with responding to name, if I say his name while playing he will ignore, but if I say his name followed by look at this car, he turns right away.  Is this concerning?  I always read that this is the number one indicator of asd.  But I wonder if he is just ignoring because he feels I have nothing to offer.