competetive sport may be throwing her in at the deep end

i always remember that i was very shy, but my dad helped me out of it in little ways like for example, when the ice-cream van came around, i would only get an icecream if i went and asked for it myself, even though i didnt want to, little things like that can break down the shyness,

just get her involved with other people as best you can, and work from there