Backward - edit

[brandontoh]

I enjoyed reading the poem! My gripes are mostly nitpicks, so yeah, hope my comments are helpful! 

Revised

At seven they reckon you’re too old
for adoption. I look on your head
so underwhelming and lost within -- 'Underwhelming' is not an ideal word choice in my opinion. The idea of being less than ideal is already illustrated really well in the rest of the poem, so the slot for an adjective is kind of wasted here. Personally I think 'oblivious' would add another layer to the characterisation of the child, but that may not be what you're going for. It's your poem. =)
that bicycle helmet, behind
four years in letters and numbers; -- I like the change to 'letters and numbers'. It makes the image clearer, though it does sacrifice the rhyme with line 7.
your inside out and backward dress
patterned with pie and snot and think
on all the words that you’ve forgot
before we’ve even turned the page -- I had to read lines 7-9 multiple times due to the strange syntax, which I'll assume is deliberate. It serves to speed up the reading of the poem and to introduce a more chaotic and confused feel to it, so if that's what you're going for it's very effective. Also, For line 9, I think that 'before the page was even turned' is a possible edit. The poem's focus is on the child and the use of  'we' detracts from that focus slightly.
on doors slammed shut and fingers bit,
the kicks of three-year-old strops and spit
now surely that must count for something? -- Although the last line end the poem very nicely, I can't help but feel that for a poem with such a melancholic feel, the phrasing of this line takes something away from that. I would suggest taking away the word 'now', because that word kind of introduces a slightly uplifting tone to the line.
 
 Original

At seven they reckon you’re too old
for adoption. I look on your head
so underwhelming and lost within
that bicycle helmet, behind
four years in reading and writing;
your inside out and backward dress
patterned with pie and snot and think
on all the words that you’ve forgot
before we’ve even turned the page,
on doors slammed shut and fingers bit,
the kicks of three-year-old strops and spit
now surely that must count for something?