Wow, to be totally and very honest, i loved the way you pulled this off. Though some bits seemed repetitive, it was all in all very effective. I'll take you through my favourite parts:

I try to dig down
way deep inside
and pull out the things
I've been trying to hide

^^ i love the imagery and the metaphors used here, very naturally done, explains it perfectly.

but I'm starting to realize
that nothing is there
and what scares me the most
is that i don't even care

^^i love the third line and fourth line. the honesty is quite cute...

I'm a shell of a person
who has no control
who has to meds
so i don't lose my hold

^^sorry i don't really understand the third line. otherwise the flow is perfect, but the third line threw me a bit.

not just the world
or everyone else
i can't see me
i can't find myself

^^well done on the third and fourth line here too! slight repitition, but very effective!

she's lost in a world
where she switches every other week
from a nice warm bed
to a crappy mattress that creeks

^^i think you meant 'creaks' in the fourth line, otherwise, perfect.

one weekend in heaven
and one in hell
I'm not happy at all
but you could never tell

^^ i love the way you explain the extremes here with vivid metaphors, very effective once again.

because of a fake smile
and a well placed mask
getting to the real me
is somewhat of a task

^^i think this is my favourite stanza. it seems so perrrfecttt! it totally sums up what the poem is about .

so ask me again
who i think i am
and I'll try and answer
the best that i can

^^an effective ending too, kind of leaves the reader thinking...

I think overall, the poem was written really really well, with an almost perfect flow, and effective imagery and metaphors to top it. For improvements, i could recommend punctuation... that would smarten it up a bit...thats about it!! =]
Don't stop writing, I'm going to add you to my favourites for this.. =]
MEZi x