My little boy is halfway to 18.

He turned 9 over the weekend, and this birthday hit me harder than the rest. Usually they’re a blur of neon-frosted cake (Market Basket does a great job), trampolines or laser tag, balloons and sweaty boys tackling one another like wild animals, usually at some sort of rented venue with oily pizza and stuffed versions of poop emojis bought with reams of arcade tickets.

This one was much the same, except for the knowledge that his childhood is now halfway over. We only have nine more summers with him.

Yeah, this sounds a bit melodramatic. He’s not going to evaporate and join the witness protection program in nine years. He’ll still be my kid.

But right now I feel suspended in a finite period that I want to stretch like taffy—a precious, fleeting few years before he sprouts facial hair and demands the car keys. These are the last gasps of little-boyhood: His leg hair is still blond, his voice is still innocent and he can still even relax to “Daniel Tiger” or “Paw Patrol” when he’s really sleepy. He still asks for made-up bedtime stories and sometimes needs help buckling his seat belt. I still cut his ragged fingernails and help him shampoo his hair. I still feel a sense of ownership over his person. I have an automatic sense of when his toenails need clipping, his hair needs cutting and his underwear needs replenishment.

But I know it won’t last. Soon enough his bedroom, now littered with He-Men and “Diary of a Wimpy Kid” books, will become off-limits. He’ll spend more time outside the house than in it. He won’t need me—not in the same, most primal ways.

This bittersweet knowledge has an upside: I find myself paying more attention to him than ever before—not in a smothering way, just in a slowing-down-time way. Instead of bolting from the dinner table to load the dishwasher, I sit there longer, watching him reluctantly munch his carrots. Instead of rushing through his bedtime story to watch “Big Little Lies,” I elongate it, adding new plot twists and characters. Instead of letting him run down the hallway ahead of me to grab his brother at day care, I reach for his hand.

Last night, he went outside to water the flowers. (One bonus of having a 9-year-old: free labor.) When he came inside, he couldn’t find me right away, because I was in the basement doing laundry.

“Mom? Mom? Mommy?” he cried, increasingly panicked.

I’ll admit it: I let him yell for an extra few seconds. I stood in the basement in the darkness, his damp swimsuit and camp backpack in my hand.

“Mom? Mommy? Where are you?”

I froze. I froze because I knew that soon enough, that little voice wouldn’t call for me anymore. I wanted to capture that sound, that plea, that ephemeral moment of need.

And then I walked up the stairs and gave him a hug.

“I’m right here,” I told him. He ran over to me and wrapped his arms around my waist, getting water from the hose all over my clothes.

“Please don’t ever leave me alone,” he sniffled in a little baby voice.

“I never would,” I told him.

I wanted to say, “Please don’t ever leave me, either.”

But I know that’s not how it works. So I let him untangle himself and run off to play.