Hi Sunny,
The first death of a close relative for me was also a grandparent, one of my grandmothers. I'm sorry for your loss as I know how close the bonds can be with our grandparents.
Shortly before she died, I had the only opportunity I ever remember to spend some time alone with her. She pulled out a box of old family photographs and sat me down to go through and tell me all about ancestors on that side. She'd never done that before. I lived a thousand miles away, so when she died shortly after I left, I wondered if she had some sort of premonition of her passing and wanted to tell the "family stories" before she went.
Anyway, pay attention to your dreams. Just when I was feeling bad about her being gone, I had a dream about her. I was in my parents' house, which was just two houses away from hers. My mother was in the kitchen with me and she left out the back door. I went to shut the door behind her and there was my grandma standing there out on the back porch. She smiled and said "Hi, Tweety" (she called all of us that.) I said "Hey, Gran, how are you?" I was feeling absolutely flustered because in my dream, I was aware that she'd recently passed away, so I was probably stuttering or something. She obviously noticed my discomfort and just kind of waved it off with a smile and said "Oh, I'm just fine." And off she went.
It was so vivid it woke me up. But you know what? I haven't felt bad since then about her passing because I knew she was okay. That was almost 20 years ago.
Watch for signs, listen to your intuition and pay attention to your dreams. That seems to be the easiest way to communicate.
Grandparents are wonderful and I hope you can get back in touch soon with yours.