Ok so ppl gave me tips on how to deal wiht my sister but i need more answers?

..ok so i know not to let her go... so what do i do now..? she wount answer my calls or IMs anything... i tryed explaing to her that i want to have more time together and that she means the world to me...but she doesnt get that when she desides to go out with her friends when she is on the phone wiht my for .5 sec that it hurts. and i dont like knowing that i cant talk to her with out someting going wrong..she had her time to go through being 15 its mine and she doesnt she doesnt respet that i need help going through it..and that she is the one i need.... please give me ways to tell her.??!!!