I want to first echo Sophie_M in welcoming you to the forums. The raw pain that you are still feeling from this devastating loss comes through so clearly in your post; I found it incredibly moving. Without knowing you or your mother, I can already tell what a special relationship you had.
My mom used to tell me that having children is wonderful, but also terrifying because for the first time your heart is outside your body– you can't always physically protect it as it goes out into the world. I think this is a beautiful sentiment and one I'm sure you feel as a mother yourself, but I also think that the same can be said for other people in our lives– especially our parents. I feel the exact same way about my mother, and it sounds like you may feel similarly. As you so eloquently put it, "How do you live without the one who gave you life?"
It is a hard question, but not an impossible one.
Grief is a long and often strange process with many unexpected peaks and valleys. Given that your mother only passed away in November, this means that you are still only at the very beginning of this journey. Time will heal this wound, but it takes patience, and work. I would encourage you to be patient with yourself and kind to yourself as you work through this dark stage of your grief.
What you say about your sleeping, the pain in your chest, and the tears– they all resonate with me and I'm sure many other people here on the forums. I wonder, given how much it seems like you're struggling, if you might consider reaching out to a GP for a referral to a counsellor? Even if not, just coming here on the forums to chat will help lighten your load significantly. No one should have to bear this burden themselves.
I hope you find the forums a supportive place, full of people who can speak more directly to your experience of losing a parent prematurely and unexpectedly. I have seen many people on the forums connect meaningfully over shared experiences of loss. In the meantime, please feel free to let us know how you are going here, how you are feeling, or simply peruse some of the other posts on the Grief and Loss board.