3.5 year old can’t sit still and struggles to follow directions

My 3.5 year old is an only child, so she’s always gotten a lot of attention and because of that she’s a little ahead in certain areas (linguistically, gross motor, etc.) Since she turned 3 she’s gotten progressively worse behavior wise (thinking it was the age) and we do a lot of 1-2-3 magic but it’s a LOT of it. Like for literally everything, because she just fights us on everything and really struggles to follow simple requests, like putting on shoes or brushing teeth or whatever. She knows how to do it, but most days won’t without me counting to 3 for her to do it. It’s maddening.

We put her in a 45 minute dance class in September, and she is by far the worst kid in the class. They’re all 3-4, and most of the kids listen to the teacher and are actively trying. She does like 50% of the time listen, but the other 50% she’s spinning around in circles or laying on the floor, not staying on her assigned dot, etc. I really thought it would get better and she was just acclimating to the class, which she says she enjoys and is excited to go to each week, but it’s been 3 months already and we’re seeing negligible improvement.

Up until now I thought it was just an age thing that she would grow out of and that 3.5 is just really hard in general. But now seeing her around a room full of other girls her age who are acting very differently than her is very worrying to me. It’s giving me the vibe that she is really going to struggle in PreK4 public school next year. It’s hard because we only have her so I’m not sure what the baseline for things are. Daycare providers seem to really like her, but they don’t give a ton of feedback.

I guess my question is, parents of kids who ended up having ADHD - does this type of instance sound familiar? What types of things should I look for? Or is this just a regular 3.5 year old kid thing?