Am I missing something?

[Stoppingstorm]

A couple of things have happened recently which has got me thinking about whether my DS has some developmental issues. He is 2.5 years old and will either be very over confident or extremely shy with new people and experiences.

We've recently put another hold on potty training as he doesn't seem to understand what I'm asking him to do.

The other day we took him to an aquarium where he was terrified of the fish coming close to him from behind the glass and I could feel him shaking. We went for a walk next to the river afterwards which he kept trying to get super close to like he had absolutely no fear of falling in.

Today I took him to the dentist where he screamed, had to sit on my knee while I got my teeth checked and he wouldn't allow the dentist to look in his mouth when it came to his turn.

Does this sound just like a personality thing or could there be deeper issues here?

He sounds completely and utterly normal. All children have their little foibles. His seem in the normal range. He is only little still. Stop worrrying.

Nothing concerning at all about any of that! DS1 is almost 3 and is very similar. I'm not worried in the slightest.

There isn't one thing there which would concern me, OP.
Your little boy sounds completely normal.

Oh, and as for potty training - I've had four children and they were all markedly different with regard to this.
This slowest was the second child (a boy) and he was over four years old before he managed it. He's a grown man now.

Children all vary. There is such a wide variety of "normal" with them.

Yep normal.