Welcome to the message boards! I hope you and your mother have a wonderful cruise! It sounds like you have an excellent stateroom.
The staterooms on the front and the back of the ship are really not that bad - personally, I enjoy them on my cruises. You don't have as many people walking by your stateroom door, so your stateroom ends up feeling more private and seems much more quiet.
I would agree that it isn't likely you would get an upgrade at this point, but they might offer you something when you check in for your cruise. You might even ask if something would be available. The worst thing they can say is no, after all. You will still have a lovely stateroom with a verandah!
As a travel agent specializing in cruises, I always encourage my clients and customers to consider a guarantee stateroom. These are usually the least expensive rates, my clients almost always get nice, big upgrades. I can only think of a very few clients in almost 10 years in the business that haven't gotten some type of upgrade. The only downside is the uncertainty because you don't know your exact stateroom until just before you leave. Also, if your stateroom assignment on the guarantee reservation is completely unacceptable to you, travel agents are able to speak with the cruise line and are often make arrangements for a new stateroom assignment for you, if at all possible.
Have a great cruise!