I'm sorry for your loss. My father also believed in being able to communicate from beyond. I asked him before death to come to me and tell me he was okay.
I will tell you, I was frustrated for a year because he hadn't come. Finally he did come in my dreams. So please, be patient. Sometimes they are in healing centers and cannot pass a sign or message until they transition completely.
Keep asking for dream signs and visits. Your loved one will come :)