Two weeks is very recent. Give yourself some time.
I found it hardest when everyone around me was "getting back" to their lives and routines and I was still pretty much in the depths of my grief. Made me feel like I wasn't moving along as well as I should have been. But, that wasn't the case. Everyone grieves differently.
Have you considered some type of grief counseling or group therapy? Sometimes just knowing that others share your feelings helps tremendously. Plus, it provides someone to talk with face to face about it.
I'm so sorry you lost your Grandmother.

It's hard to lose someone you love. It sounds like you loved her very much. Shelley gave an excellent suggestion to write about her. I've done it and it helped me. Plus, we'd love to hear some stories about her if you'd like to share them.