Similar ideas, and we also have many dissimilar ideas.

It also seems to me that we are not able to understand each others ideas thoroughly because we have a different understanding of some words.

In order to try and clarify the differences I'll insert some questions and comments to what you posted.

Actually, I was suggesting that black holes only expand, they never contract.
They only grow bigger. Stephen Hawking has theorized that black holes can evaporate and get smaller. I haven't seen his formulas, and I haven't read about any evidence for such a phenomenon, so it hasn't been proven. Anyways, the Andromeda galaxy is due to collide with our Milky Way galaxy in about 5 billion years. Even if the central supermassive black holes miss each other, they could each capture hundreds of millions of stars and become extremely bloated. Subsequent galactic collisions would hypothetically become more frequent, according to my simulation, and the central black hole growth will accelerate.

I assume that you consider the black holes as being composed of very high density mass.
But then, could not this black hole area be the opposite of high density mass, that is, an extremely low density mass or emptiness within the space-time continuum.

On a larger scale, if our universe is also a black hole within a larger universe, then it's growth will accelerate, but then abruptly stop growing, having acquired the entire mass of the parent universe. There will be no big crunch, no big rip, only growth from the inside. I suppose I could call my hypothesis a theory based on the experimental evidence of the accelerating expansion of the universe. But that's just one piece of evidence and I'm not satisfied with just that.

Interesting idea, but again, you are assuming that the "black hole" is made up of mass.
No one has seen into a black hole, so we really do not know what is in there.
We only suspect that it is composed of mass because it has a very high gravitational field associated with it, and mass has the same gravitational property.
But should we not understand how gravity originates within mass before assuming that black holes are made up of mass.
What if the gravitational force within mass is the result of the amount of empty space that is intrinsic to the mass, then the black hole would simply be an empty area.

There is still the question of what medium supports the largest black hole? Turtles? We used to think the earth was flat and supported by turtles. Now cosmologists think the universe is flat. LOL. I think that event horizons are not physical things. They exist only as a mathematical consequence of more basic things, such as fundamental particles. Therefore nothing exists outside the largest event horizon. There is only an outside to our universe's event horizon because it has not yet enveloped the maximum mass allowed by the "field" that supports matter and energy. So it grows until it reaches the total mass of the quantum field. I think the largest possible event horizon has no "outside", just as it has no physical substance. It is an emergent mathematical phenomenon.

How do you envision a cubic area that has nothing in it? I consider it as empty space.
You imply that there must be a "field" that supports matter and energy.
What is your definition of the words, "matter" and "energy".?
In my opinion "matter" consists of "mass", and "energy" is the internal or external motion of "mass".

If one had the ability to affect quantum fields, one could affect the whole universe. But what supports the quantum field? That's got to be a mystery. Spooky too. The math seems to be rather non-intuitive. Truely alien.

For the math, I would suggest starting with E=(u/k)c

Johannes