I'm sorry about your mom, my mother also passed away. While I can relate on some level, I know the way everyone deals with death is unique.

In my own experience, any time my mother has appeared in a dream, she is weak, sick, and frail. In the dream, nobody seems to realize this; we are just joyful she's back, and life continues with her now apart of it. It's not until I wake up that I realize the state she was in. She died of cancer, and I used wonder whether or not her physical state in my dreams has a connection with my lacking memories of her in good health.

The dreams can make me feel cheated because I don't get the full experience. But I remember that each second she spent here with me can't be taken from me. After a dream like this, I do my best to recall my most joyful memories with her.

I encourage you not to worry that your mom hasn't appeared to you in some way, whether through a dream or feeling her presence. All the same, when (because I'm sure it will happen) the day comes where you do dream of her, embrace it, and don't let them haunt you. For a long time I believed that my dreams of my mother showed some flaw in my opinion/thought/memory of her, but my dreams don't change the facts about my mom: she was strong, loving, and faithful.