Hello Heather.  I am so sorry for your loss of your sister.  Grief is a strange thing.  I knew a Man who lost his baby sister and it took nearly 20 years before he was able to cry about it.  When I lost my Mum it was many years before I actually cried for her.  I think that for some people, we simply shut down emotionally when we lose the people we Love, because that's the only way we can deal with it at the time.  There is no 'right' or 'wrong' way to grieve...........we all get through it in our own way.  There is certainly nothing unusual in your reaction, and at some point, your tears for your sister WILL come.  There will  come a day when you are able to talk about her and although it will still hurt, you will find that the awful, raw pain you are feeling right now will have eased off, and you will even be able to laugh at some of the treasured memories you have of her...........for example, the good times you had together and the times she made you laugh.  Once again Heather, so sorry for your loss, take care, xx