In “Another Happy Day,” Lauren Lapkus plays a new mother who knows she’s no good at mothering, a frustrated, sleep-deprived young woman feeling lost and alone until she meets that not-quite-relative who says what she most needs to hear.

“I hope you’re not going to be talking about your baby because I am truly not interested.“

Writer-director Nora Fiffer’s debut feature shows us the tears and hopes that we understand them. And she finds humor amid the insights about this particular version of post partum depression.

Joanna (Lupkus) tracks via her phone timer how little baby Alma is sleeping and weeps at the little sleep she herself is. She’s learning to let the phrase “You have poop on you” roll off her back and can’t process that her newborn still isn’t looking at her.

This is “the loneliest I’ve ever been.”

Partner Lucien (Jean Elie) works. Her mom won’t come “help” despite her fervent pleas/ And her peers either don’t have kids and just don’t get it, or expose her to the insipid mewling that is every baby shower she’s invited to.

Visiting her old graphic design workplace just triggers her mood swings, as she leaps from relieved to finally be talking with other adults outside of her apartment, to craving getting back to work to paranoid to permanently unemployed there thanks to finally crossing a line with a boss (Carrie Coon of “His Three Daughters”) who at least starts the conversation with sympathy because she’s “been there.”

But Mom remembers this one relative. Well, she USED to be a relative. Miriam also lives in Chicago. She used to be married to your Uncle Leonard, but that was years ago. You won’t remember. Go see her!

Miriam is quite old, but still a working actress, she insists. She has a big, rambling apartment and little to no interest in “family,” “babies” or even Joanna.

“But you can come here,” they eventually decide. Just yank out an unused dog bed — “It’s for babies!” — and sit together, keep the “chit chat” to a minimum and maybe run lines with the self-absorbed older woman.

Fiffer uses this dynamic — of course Miriam has her own secrets and “issues” — to guide Joanna to insights about her own adulthood and her child, whom she jokingly refers to as “this parasite.”

“She doesn’t love. She just needs.”

Lapkus does a mercurial turn here, serving up a young mom who is manic and panicked, exhausted and depressed, and who still remembers what it feels like to be funny and even witty “in my real life.”

Every generation experiences this trial of child-bearing anew, but Fiffer and Lapkus (“Orange is the New Black,” “Crashing” and “The Big Bang Theory”) show us the phone-search-what-that-white-spot-on-my-nipple-is parents, lost and struggling with the art of “adulting.” Joanna is still prattling on about her ambitions and her “dream” when Lucien, cradling their child, is here to remind her that “This IS the dream,” at least to some people, those who don’t prefer dogs or cats and travel and a career.

None of it could be called “deep.” But there are grins and laughs of recognition in all these sweet, unassuming “It’s your turn to think you’re reinventing parenthood” insights.

And yes, hospitals still give out lots of helpful pamphlets and website addresses, all of which have but one message to every new mom and dad.

“Don’t shake the baby!”

Rating: unrated, profanity, scatological humor

Cast: Lauren Lapkus, Jean Elie, Marilyn Dodds Franks, Tim Kazurinsky and Carrie Coon.

Credits: Scripted and directed by Nora Fiffer. A Gravitas Ventures release.

Running time: 1:30