I know that I went through a lot of different grieving stages after my mom passed away. First I don't think it sunk in for a while, then I was really sad, then I cried myself to sleep every night, then I was mad at her, then mad at me, then missing her all the time. But finally after about 1-1/2 years I think I finally reached the acceptance stage. I still miss her and love her so much, but I've had to go on with my life. I'm still always a part of her and she a part of me. I have my memories and I know that someday I will see her again and for now that will have to be enough.
My stepdad had me go back down a couple of months after she was gone and go through her things. I really was dreading the trip. I took the kids and we spent the first few days just trying to ignore the reason I was there. Then finally I started going through her things. It wasn't as hard as I thought it would be. I took a lot of her clothing and things to a thrift center that she always liked shopping at and divided up her jewelry for my sister and I. It wasn't easy, but I knew that it would really help my stepdad. He thanked me for doing it and said that it made it easier for him to be in the house.
You are going to have a lot of different feelings and emotions. Just accept them and realize that they are normal. You know that your dad loved you and that you loved him, that is what is really important. I think it's also great that you are becoming closer to your sister. My sister & I are closer than we ever were before. You'll get through this ok.