While i am hardly qualified, as a 16 year old in high school, i'd like to offer a critique anyway.
i really like the overall theme, it connects with me and that's exactly what makes poems powerful.
the ending line also connects, as well as leaves me with a (fairly strange) feeling of warmth and yet some chilly sadness of days lost. I really enjoyed the word choice and innocent, childlike voice within this poem.
overall, the poem is very powerful. i personally would say a little on the over-long side, but that is again a personal opinion, and i'm certain others would disagree.
great poem, i really liked it.