If the suggestions in the article aren't helping, I recommend you start therapy. You've already identified the issue—being parentified—so you can find a professional who has experience with that, jump right in, and not be delayed by superfluous issues. The therapist can give you advice on how to maneuver the relationship with your mother, whether it's through minimizing contact or by developing strategies to finally end the role-reversal. You've dealt with this your entire life and know nothing else so it's little wonder you're struggling and could use professional guidance.
Some psychologists see parentification as a form of child abuse and, because of my own decades-long struggle with it, I've come to share that belief. It's a tremendously difficult thing to overcome. I've found peace, though, through acceptance. I accepted that my mother enjoyed the parentified relationship we had, but I no longer did. I accepted that I'll never have a warm, loving, and supportive mother. I accepted that minimizing contact with my mom was the only way that I could be a good wife, attentive parent, and an emotionally well-adjusted human being.
I also accepted that there was a part of me that didn't want to give up the role as my mother's wise counselor and trusted advisor. I had played that part for so long and felt a loss of identity and purpose when I surrendered it. My mom didn't know how to have a relationship beyond that dynamic. She didn't know how to be maternal with me or grandmotherly with my kids. Therefore, it was inevitable that we'd be at odds and need to separate.
A good therapist can help you cultivate reciprocal relationships. You, however, need to put in the hard work of changing the way you interact with the world, becoming more vulnerable and learning to trust. Once you begin making changes, finding your voice, and seizing control of your life, you'll feel less lonely and depressed.
The spiritual teacher, Iyanla Vanzant, said something that I found useful to me as a parentified child: “There is no greater battle in life than the battle between the parts of you that want to be healed and the parts of you that are comfortable and content remaining broken.”
As parentified children, we know how to be sad and isolated because we've done it our entire lives. That's why we could use a helping hand to become something different. Take care!