With four short words, my son lets me know I’ve blown it. I’ve overstayed my welcome. “Mama, no work now.” His sticky, banana-covered hands reach up for me and his certainty that I will not leave him there breaks my heart.

Because I will leave him there.

I give one last hug and turn before I can see the trembling of his lips I know is coming. I know he will be fine once I am gone—he loves his friends at daycare and today is a birthday celebration for one of the children in his class. He’ll have a great day. He will soon forget about these emotions. But I won’t.

Ice-encrusted trees line the parking lot. They sparkle in the morning sunlight as I start my commute and fail to distract myself from the guilt wrapping its arctic fingers around my heart. I feel his younger brother kicking and rolling in my belly and berate myself for leaving one son behind while I carry the other with me all day.

Sure, it’s a Wednesday and I need to save my time off for my upcoming maternity leave, but I could have called out. I could have played hooky and taken my son back home with me for a day of mom and toddler playtime before his baby brother arrives and his entire world shifts. I could have, but I didn’t.

We were warned from the start about the fine line when it comes to daycare drop-offs: Don’t stay too long! We have to get in, put his lunch in the fridge, his energetic toddler self into his seat at the breakfast table, wait for him to peel his banana, and then say, “goodbye-bud-have-fun-today-I-love-you,” and get out.

This usually takes all of five minutes. This usually ends simply and pleasantly for all involved. Toddler happily sits down to enjoy his morning snack next to his friends while Mom (or, more often, Dad) sneaks out after a goodbye hug to rejoin the morning rush.

A normal day is had by all. He’ll play trains and sing the “ABCs” while my husband and I solve puzzles of grammar and nature’s disregard for a planned construction timeline. This has been our usual routine for more than a year and a half.

Usually, the workday is uneventful. Usually, I don’t have to make a conscious effort to not obsessively text his teacher and ask how he is doing.

Today, I learn where the fine line is for us: I ran straight through it. I hear him cry for me long after I’m on the highway. In every sentence I edit, every page layout I proof, I see the ways things did not fit into our tried and true pattern and why it is all my fault.

***

I edit and publish technical standards for a living. These standards are used to help keep trampolines and roller coasters safe and crayons non-toxic. Like the scientists and engineers who develop the standards, a portion of my work is conducted on a trial and error basis. It’s thrilling and frustrating by turns.

Hours tick by at my desk as I fiddle with the page layout of a new testing standard, trying just one more tweak to the tagging to see if I can get the graph to fit where the authors wanted it on the page. I asked a colleague in the art department to try resizing it, but we can only go so far: aesthetics mean nothing if the data is unreadable.

Eventually, I send the file to the technical expert who will review my edits. In my note, I add a caveat about the design: I’m still working on this! I’ll get it sorted before we need to publish. I promise to make things perfect, or as close to perfect as the technology will allow. Engineers are typically tolerant of technology-imposed limitations. Human error is harder to forgive.

***

Another day, I arrive at daycare for pickup earlier than usual. It’s a federal holiday and the highways are nearly empty. I stop myself from doing the math, agonizing over how much of my life I spend sitting in traffic when I could be at home. I’ve learned it does no one any good.

I walk across the yard to find my son and four other children playing in the sandbox, sprinkling sand from one dump truck into another. JJ, my son, has a splotch of sand on his cheek. Toddler babbles punctuate the summer breeze.

"Jay! Ready to go home, bud?"

"No." He shakes his head, his golden curls swishing around. The motion captures his attention and he watches his hair skirt above his eyes. Back and forth. Back and forth. Another child drops a toy.

"Uh oh," JJ sympathizes. I chuckle as he proceeds to commandeer the vehicle for himself. The little girl shrugs and picks up a different truck. The sand construction continues.

I try a second time, reminding him of the playful hound dog waiting for us at home. "Jay-man, want to go home and play with Zoey?"

He squints up at me briefly. "No no, no, no."

I leave him with his friends, happy in the care of his daycare providers, and go inside the building to collect his things. I’ll try again in a few minutes. His note for the day says he was helpful and energetic, and he’s actually worn the new hat we sent in, the one with the football logo just like Dad’s hat: Thanks for thinking of it! his teacher wrote.

***

It feels as though motherhood is spent in the trial-and-error trenches. Is the baby hungry? Wet? Tired? No? Does he want to be laid down? Held? Rocked? Oh, he wants to be bounced, in one specific motion. Will he sleep better unswaddled? With just one arm loose? What if we try a dream feed? A different sound on the white noise machine? Should one of us sleep on the nursery floor? Does he like peas? What about spinach? Will he eat peas anyway, if we hide them with pears and zucchini?

The thing about trial and error is the longer you work at it, the more failures you have already discovered—and the closer you come to finding what works best. There is no technology to be blamed when things don’t align properly in parenting. The error is human. Sometimes the error is mine, but I’m still working on it.

Guest post written by Stephanie Heilman. Stephanie is a wife and mama editing professionally and writing for fun in southeastern Pennsylvania. She believes passionately that there is nothing more powerful than the stories we tell about our selves and others. You can find her on Instagram and sometimes Twitter, and when she's really feeling gutsy, she shares some writing on her website.