Although several varieties of plum trees are self-fertile and are able to pollinate themselves, many require another variety nearby for pollination. Since, what I hear you saying, is that you've had very little in the way of plum production since you planted it, I would plant another variety close by before the stertn taling to results in a dejected plum with no reason left to live...
The other possibility is that you planted an ornamental plum, which will never produce any appreciable fruits... in which case, perhaps you're the one needing a stern talking to...