Bless your heart, Jezebel Jasmine.
Your son must be a little ray of sunshine at your home.
I am not an expert in this area, but will share what I know.
My nephew is 22 and has CP. He is at the level of about a 4 yo,
but does not walk.
He is also the size of a man.
He is just one of those kids that everybody loves and a great hugger.
Nephew is also the #1 fan at all the school sports events.
He has an electric wc for accessability.
Purposely, my sis & her family moved to a one story home because of all the lifting.
Ramps are at the front and back doors.
Sis is the the point, she can barely lift him any more.
Her back is nearly ruined from all the lifting and trying to be the best Mom possible.
Her health has suffered for this.
If falls mainly on his Dad to handle the lifting now.
They do have a basement downstairs with one of those electronic chairs attached to the wall that goes up and down. Nephew does not spend a lot of time down the basement,
but he does have access, if he wishes to go down.

There are also vertical platform lifts. I noticed one of these outside a home
just this morning.
What happens if you fall, Jasmine? You will both go down and get hurt.
That is really scarey.
There are also small elevators that can go into homes, but those are $$$.
Your dear son will only grow larger and heavier as he gets older.
Is it possible for you to move to a one level home/apartment, wheelchair accessible,
with no stairs?
Please let us know what you decide.
(((Hugs)))