Could she possibly have ADD or something similar? While a lot of people claim to have it even though they don't(making the symptoms rather vague), it's possible she actually has it, and it's the reason why she never really pays attention to you.

My own parents tend to forget things mid-sentence and start talking to other people when I'm speaking to them, even when it's important, but this became more frequent after some close relatives of theirs had passed away. The stress from their deaths as well as simply growing older might contribute to things like short-term memory loss, so please keep that in mind about your own mother.