Given the time that you have, the simplest answer may be to have the dog registered as an “assistance” animal for your son. Now, when I say “simplest” I have no idea how difficult that might be but if you can achieve it, the Owners Corp can’t refuse your dog.
Have a look here – and then take it up with your local council.
By the way, saying “it’s my own property” is not going to get you the approval and support you might need. When we choose to live in strata we give up some of our individual rights as home owners so as to enjoy the collective benefits. If you don’t like the by-laws, you get involved and persuade other owners to change them.