The other day my five year old daughter and I were playing on the floor in the living room with her little sister.

Suddenly, my 3-year-old son came racing through with his superhero cape on, just narrowly missing the baby. Entirely unfazed by the potential collision, she pushed up on all fours a la downward facing dog and held herself in place for a few seconds before dropping to the ground and army crawling after him.

Oh, you’re such a big girl! I squealed. Please stop growing!

But, mama. My oldest protested. Why would you want that? Don’t you want her to be big and strong like me?

As I glanced back and forth between my two girls, a lump formed in my throat.

Of course I want all of my children to grow big and strong. (And kind. And curious. And generous. I want so many things for them…) I just wish it wouldn’t be happening quite so quickly.

I’m pretty convinced that time speeds up when you become a mother.

With each baby we’ve brought home, it’s only gotten faster. They progress from newborn to infant to baby to toddler in just a few years. Then, like my oldest this fall, they are off to Kindergarten and not so little anymore.

And so I find myself at a parenting crossroads. Suddenly all of the “firsts” we celebrated so enthusiastically with our first two children—first night sleeping in their own room, first steps, first words, first day of preschool—now seem bittersweet.

Every time one of my kids reaches a milestone it’s exciting, but it’s also a sobering reminder that this phase of our children’s lives is approaching its end all too soon.

And so I welcome my oldest into our bed when she has the occasional bad dream, because someday soon she won’t come snuggle anymore.

I carry my now three-year-old more than I probably should, because someday soon I won’t be able to lift him so effortlessly.

I keep our baby in our room, not because she isn’t ready to be in her own space, but because I’m not quite ready to let her go.

I try to unplug and live in the moment. Yet somehow my heart aches for time to slow down even when I’m fully present.

As much as I would love to push pause and keep my babies “my babies” forever, there are also things I look forward to.

I’m excited to jump in a car and go without worrying about car seats and booster seats and strollers. Grocery shopping without a temper tantrum in the middle of the store. No more diapers. Or potty training. I welcome the day I no longer have to clean up poop.

I think about their futures, too. I wonder what their interests will be, what things they’ll choose to pursue and how they’ll handle things when life gets hard. Because it will. And I hope I will have done enough to prepare them for those moments. I can’t wait to see who they will become.

I don’t want my babies to stop growing. Not really anyway.

Still, as I watched my baby scootch across the floor on her tummy, the lump in my throat grew larger. At six months, she is in that sweet spot of babyhood. No longer a needy newborn, not yet a fully-mobile. Everything is impressive to her. Every day she accomplishes something new. I felt proud and happy and sad all at once.

Why can’t she be little forever?

I took out my iPhone, snapped a photo and took a video of her siblings playing with her. I hope that when my kids are grown, these images will bring me back to this exact moment.

It’s going by way too fast.

I put the phone away and got back down on the floor with my family and reminded myself that the best is yet to come.