I do believe there is some kind of presence for our loved ones after we have lost them, I've had things happen which feel like messages. I picked up my mobile to make a phonecall one day, went to phone book and I have a favourites page which shows a thumbnail photo and name, and all 9 contacts had changed to my dad. I took a screenshot, and then it disappeared and went back to normal.
I saw a friend of a friend for reiki for a while and felt benefit from it. She used to do spiritual work, and after I lost my dad she was doing reiki on me and she was 100% convinced I was pregnant and had messages from my dad about it. I knew I was 100% not pregnant, but thought I'd text my sister to see if she was - and she was (she hadn't told anyone yet and hadnt made it known she was considering it either). I dont know if this proves anything but felt like she was being genuine (dont see what she would gain from it otherwise)
But I do have the concern that some mediums are not genuine and are taking advantage of people. I dont know how you can confidently find someone genuine xx