Hi 6th Sensemy Mum passed in 1994 and I was in the same position as you. I had a lifelong fascination for spirituality. She did indeed visit me a lotI began to feel her presence around regularly. I had a few dream visitations, especially in the first year.
One of the first visits was on the night she passed when my door banged repeatedly but she could not get it open. I regularly heard "clicks" in mid-air, and the candles we lit for her were often "played with" (especially the wicks would form little flowers). On the 49th day, a red candle we lit appeared to have melted overnight, as though a knife came down on it.
Earlier this year, she put up the pillow on her bed as though she had been resting there, so it was really nice to get one of the biggest physical-world signs she was still around.
I do not believe her to be stuck here but that she freely visits us and spends time with us.
Please say hi to your Mum and let her know you are enjoying her visits. Having been through what you have, I can say that the sense that she is around remainsit is not too different to the feeling I had when I was at school and she was at work. I just knew she was there for me. The only difference is that I dont get to hear her (I cannot get my clairaudiant sense to work well) and "seeing" her takes a slightly different mode.