I think one of the worst thing you could ever do
to complicate the gravity of your own situation is to express your
liking for her JUST BECAUSE she seemed to be avoiding you. In your
mind, you probably think that your chance may be ruin if you don't
employ enough haste, thus your expression.
In all likelihood, she probably knew that you liked her even before
your expression, which is why she opt to avoid/send you cold
messages because she has an unrequited love from some other
guy.
In simple words: you took uncalculated risk and lost much of your
unused chips.
She seemed defensive when dealing with you; it would be a hard nut
to crack if you wish to explore her emotional realm.
IMHO, I think you have lost much of this battle. Reason being the
way you handle her. You could attempt to reverse this trend, but do
exercise enough caution to avoid becoming an irritant in
impression. You see, people don't treat someone coldly for no
rhythm or reason; it just so happen that you don't know the reason
behind. There are a number of possibilities - so instead of trying
to force it out of her, you could try to source it from people
around her. 
Cheers
