Monday night, with my husband and I running beside him, 6-year-old Sammy learned to ride his bike.

Dad let go of his shirt. His feet pushed the pedals and he held the handle bar steady. He rode all by himself, leaning on no one for balance.

Dad pumped his fists triumphantly in the air. I tried to laugh, but was running so hard to keep up, that I choked on the air and just coughed instead.

We celebrated the milestone all night, with calls to both sets of grandparents. Sammy went to bed proud, strong and confident.

I went to bed with a tinge of panic.

Sammy, you see, is constantly wiggling one of his baby teeth, insisting it's loose. Someday, too soon, it will fall out. He'll put it under his pillow and fall asleep waiting for the tooth fairy.

And my baby will not be a baby anymore.

Then, who will I be?

Sure, I'll still be a mother. But not the kind that wipes noses, ties shoes and puts Band-aids on mosquito bites because, to a 6-year-old, Band-aids cure all.

I'll be a mother to a first-grader and then a second-grader and then a third-grader who doesn't need Band-aids at all. In the blink of an eye, I'll be mother to another teenager (my 12-year-old stepson Taylor is so already there.) I won't be tucking anyone in. Instead I'll be having talks about drugs and alcohol and how Sammy's eyes are going to get stuck in the back of the head if he keeps rolling them like that.

Go ahead. Call me overly dramatic - everyone else does. But for the last six years, I've built an identity around mothering this white ball of skin and appendages. Now, that white, wiggly ball can ride a bike. Soon, it will lose its first tooth.

Then what? School trips, size 12 shorts, trophies, girlfriends, college, grandkids. OK, so maybe I'm getting ahead of myself.

But you have to understand this bike-riding thing. It had been my motherly mission to get Sammy riding for the last two summers. I held up Taylor for the first time on two wheels when he was 5. Sammy's cousins learned when they were 4. Why was my little guy - 5 and then 6 - having so much trouble? The possibility that it was all my fault nagged in the back of my brain.

"You're pushing too hard," I would tell myself.

"You're not pushing hard enough."

I'd come home from work too tired to run along beside him. And when Sammy said he never wanted to learn - ever - I was too tired to convince him otherwise.

Then, last night, we took the training wheels off of Sammy's bigger bike. The small bike was too hard to steer, we reasoned, even if the big bike meant a longer fall to the pavement.

Suddenly, Sammy was a bike rider. My baby boy was just a boy. Sammy made the "milestone" phone calls that map a child's growth. He will make another when that darned tooth falls out.

But, really, I have to keep it all in perspective.

Every time Sammy does something to remind me just how big he's getting, he does something else to secure my role as a doting mother.

Recently, as my husband and I piddled in the yard, Sammy opened the patio door and looked over the high porch. Then he yelled - loud enough for all the neighbors piddling in their yards to hear: "Mom! My my butt itches."

Yeah, I thought, climbing the porch stairs. He still needs me.