It does sound as if this could be the beginning of Alzheimer's, but there are a number of things that would need to be ruled out first. Really, what she needs is a complete check-up with blood tests and maybe even a head CT if her provider feels it is warranted. (In my area a head CT is generally part of an Alzheimer's work-up. Obviously there is no "official" test for Alzheimer's, but a head CT can rule out other issues such as a brain tumour or bleed.)
What I'd strongly recommend is that you talk to her doctor in advance about your concerns. Given what you've reported about her forgetfulness and repetition, it's quite possible that her insight is very poor. It's common for people with dementia to forget that they have memory problems. They can't remember that they forgot something, or that they got lost, or that they couldn't do something, because their short-term memory is so poor. This means that she may indicate to her provider that she's better off than she actually is. I had a practicum at a geriatric clinic, and we normally insisted that a family member or friend needed to accompany the patient for a geriatric assessment, to provide collateral history. It was common for the visit to go somewhat along the lines of, "My memory is pretty good", and then the support person would say, "Wait, Mom, remember you had that issue last week/month/recently?" Even if your mother won't allow you to accompany her to a visit, you can still call her provider and indicate your concerns. While her provider can't share her medical information, they should be able to listen to you and this will give them a heads-up as to what may need to be done.
There is also the question of capacity. You'll need to find out what your area's laws are in this regard as they can vary. I believe it is generally accepted that until proven otherwise, it is presumed that an individual has capacity to make his/her own decisions. This means that your mother may have the right to live at risk unless something serious happens that causes her capacity to be questioned. Your local seniors' resource agency may be able to provide you with information on capacity determination regulations and processes in your area.
I'm so sorry you're going through this. I've cared for many patients with Alzheimer's and other dementias, but only recently began to experience this as a family member as my grandmother was diagnosed with Alzheimer's a few years ago. She now lives in a care facility. I hope that something is able to be done for your mother.