I'm so sorry to hear about your mom :(
Keep trying; good things happen to those who wait! :)
I have not used a medium, but ask Reverand Ruby... she's sensitive :)
I believe I'm sensitive to an extent... but I can not read the living to get through to the dead. The deceased just sometimes talk to me and catch my attention.
Maybe ask your mom if it's possible for her to visit you in a dream... after my Uncle Brian passed away (he was also my godfather), he came to me in a dream... towards the end I was SO upset, didn't want to wake up, but he literally smiled and pinched me in the dream (something he totally would have done in life) to wake me up ;)
My step MIL has had recurring orb experience in her house ever since her father passed away. He's still around in a slightly physical sense. It calms her a lot (although she'd never tell anyone about this, she was a skeptic until this started happening).
You already know your mom is still with you, and she will continue to live on through your memories and through your heart :)