How can i approach this girl? I know she likes me

Hi all, I am 15 years old this year and schooling. When i was 13 there was this girl who kept looking into my eyes wherever and whenever i am, i didn't like her at first but after 1-2 months i started to think about her everyday. I am very sure she likes me.

Over these 2 years i tried to ask her out but she say she's busy(I think its an excuse, i dunno why). Until recently whenever we meet, she always turns her vision away and not look at me on purpose, i tried talking to her but its always a one word answer, i can feel that she's very nervous, me too.

We can talk perfectly ok through SMS but in real life, we can't. I think she's very shy but can someone advice me what can i do?? I want to start a relationship with her but we can't seem to break the ice :(

Does she still likes me now? She keep looking away on purpose in front of me but looks at me from a far