And since the even the whole groups of galaxies are gravitationally bound, it seems that the galaxies, including our own galaxy, are not "stretching" but remain the same size. And, based on the same principle, everything inside of them also, including us.

So back to the cupcake analogy, the raisins are the whole galaxy groups.

Also:

https://medium.com/starts-with-a-bang/this-is-why-we-arent-e...

"As physicist Richard Price once put it, “Your waistline may be spreading, but you can’t blame it on the expansion of the universe.”"

https://www.newscientist.com/article/dn8082-cosmic-expansion...

https://arxiv.org/abs/gr-qc/0508052

Here "bonded to other matter" means "electrostatically attracted together".