dear tina, I feel the dream state is the most likely area for most of us for those passed on to speak to us. the feeling of having imaginary conversations is self explanatory for us who remain behind and have no tangible hands on sensory apparatus to convince ourselves it is a real conversation. however that does not mean you should cease to try and get contact thru this method. since you already do talk to her, it remains for you to trust that you are heard, that your thoughts will attract her to you. she loves you and so love will often pull them towards us..all mothers the world over fuss and fret over their children, death cannot separate us.
after you release your conversation with mother and forget about it, she will be preparing how to reach you, as I said most likely for many of us, the dream state.
however you may pick up her presense in other ways if your mind becomes open and expectant. the distance between your question to her and her response arriving is in direct association to your trust level and your open mind. for me, a week or two is even needed before my intentions to have a question answered will indeed be answered.
always pat yourself on the back despite it may take this long or longer. patience is a virtue and trust is not easy to come by on our planet, and neither is open minds.
you have a head start..I say go for it!!!!