Overall, I think you are ready for a dog. I hope you understand that with any young dog and some older ones shoes, books, etc. have to be picked up or the dog will destroy them. To meet your mother's needs of a trained dog do not get in a hurry or take the first dog she thinks is ok. It will be your responsibility to make it work or you may have to give the dog away.
Look for an adult dog that is already trained. There is no perfect dog. Always ask about the negatives. Ask what the dog does wrong, and about special needs or habits.
- Contact rescues for the breeds that interest you. There are often dogs available who belonged to someone who had to move and could not take the dog, someone had allergies, financial difficulties or an older person who could no longer care for the dog. The rescue wants the dog to go to the best home and for you to be happy with the dog. So, be honest with them about your experience, being a first time dog owner and your mother's concerns. Ask if you can take the dog home on a trial basis. People in rescue usually know a lot about the dogs because they live in the home of the rescue member.
- Go to akc.org. Look at the Breeder Contacts on the left side of the page of each breed that interests you. Occasionally, breeders of show dogs need to rehome one of their dogs because it will no longer be used for breeding, they need to bring in new genetics, etc. These are often trained, retired champions that would make wonderful pets. They are known to sell at a lower price to a good home. Reputable breeders also know the details of the dog.
- Local shelter: Sometimes they know, often they don't, the background of the dog. Our local shelter will place a person on a waiting list for a particular breed. No obligation to take it if one becomes available.
- Vet clinics and Groomers: Make a 1 page flyer with information on what you are looking for. Ask them to contact you if they hear of someone needing a home for a trained family pet.
- Craigslist: Be very careful because some people misrepresent the family pet they have available.
- petfinder.org . You may find a dog that is within driving distance of your home.
While looking check out obedience classes. Observe classes to make sure they use positive reinforcement.
The day you get your dog home start house training as you would for a pup. Scheduled trips outside. Crated when it cannot be watched. Feed at scheduled times. Take walks on a schedule. This will allow the dog to adjust with little potential to upset your mother.
You have your work cut out for you. I hope you find it a labor of love.