Struggle

I'm struggling a little with my youngest growing up...I know he's no longer a toddler (he's 4) but luckily for me, he's on the smaller side and so still feels like my baby. And the best part, he still lets me cuddle and kiss him, and every day he says, "Mom I love you the most!".
The other morning i was cuddling him in bed and I said, "I don't want you to grow up." and he replied, "But I have to!"... It was a bitter piece of truth that I do not yet want to taste....