What does the poet of "A Photograph" intend to suggest through the words "the laboured ease of loss"?

In this poem, Shirley Toulson writes of gazing at a photo of her mother at the beach with her cousins. The photo was taken before Shirley was born in 1924, and she used to look at it with her mother. Her mother would laugh looking at the photograph, remembering those beach days and the clothes they would wear. The mother's memory was of the events at the beach; the speaker's memory is of her mother laughing at those memories. The speaker says the memories are:

Both wryWith the laboured ease of loss

The word wry means ironic or mocking and wry can have a connotation of bittersweetness. If you smile wryly about something, it is with mixed emotions. Wry can also mean twisted or bent. So we could also say the memories are twisted by the sense of loss.
"Laboured ease" is a contradiction or oxymoron, and expresses a paradox, or seeming contradiction, that turns out on examination to have some truth.
What Toulson is saying is that we labor—or work—to feel easy (lighthearted) about loss. When we look at a photo, we are, paradoxically, looking at something we have preserved—an image of a past time—but also, inevitably, at a time that is lost.
As the speaker's mother tried to laugh lightheartedly over her lost girlhood at the beach, so the speaker tries to lightheartedly remember the laughter of her now deceased mother. Yet this ease is twisted and bittersweet—the speaker and her mother both work to achieve it.

The relevant lines from the poem are "The sea holiday/was her past, mine is her laughter. Both wry/With the laboured ease of loss."
The speaker is looking at a photo of her late mother as a girl enjoying a holiday at the beach. Her mother was clearly very happy as she frolicked gaily on the beach with her cousins. And the speaker, too, is happy at recalling her mother's laughter. Yet both these sources of happiness are no more, and so they are tinged with a certain sadness. They are wry in the sense that the speaker's late mother lost her happy childhood memories, and the speaker herself lost her mother.
"Laboured ease" is an oxymoron; that is to say, a contradiction in terms. Ease, of its very nature, cannot be labored. And yet the speaker uses this expression to convey the sense that both she and her mother struggled over a long period of time to deal with their loss, yet eventually did so. Once they accepted their loss was final, they were at ease.
http://www.english-for-students.com/A-Photograph.html