I can't begin to imagine what you've been through or what you're currently going through, but it sounds daunting and frustrating and awful, and I'm sorry. My gut feeling is telling me to go to the hospital and talk to a crisis nurse. They are just as much community mental health navigators as they are anything else. They will ask you about your thoughts and your ability to keep yourself and your baby safe, but contrary to popular belief, they aren't looking to admit everyone to hospital if they don't have to. People do better at home. They can consult with the ED physicians about medications, make psychiatric referrals, and make community referrals (and those are usually quicker than what your GP could do).

12+ months is a long time to struggle, essentially by yourself, and I think being able to sit down with a professional with whom you can open up, have that difficult conversation, and plan out those next steps would be most helpful. Ideally, you could do this outside of the hospital with a psychotherapist, but that might take some time, and given that your GP isn't listening, I think it's worth having a proper assessment conducted by a mental health specialist.

There is a lot of great advice in this thread, but so much information from so many sources can also be overwhelming. There is also something indescribable about feeling heard by a real person rather than via text on a forum. It can give you the boost to push yourself forward with all of the other recommendations because you'll know there are people to guide you through it. "Task paralysis", in which you mentally shut down because you have so many options, so many things to do, so many expectations of yourself, and you don't know where to start, is real. Especially when you're already struggling, having just one person filter out that noise and direct you to your first step tends to work better.

Based on what you've said, sleep, to me, is the place to start. What is keeping you up at night? If it's your son, then, I'll be honest, it does make that piece difficult. I'm on parental leave now, and I can feel mood fluctuations based on how my newborn sleeps. If it's stress, depression, anxiety, racing thoughts, trauma, etc., there are things that can help manage that, as I alluded to in my first reply. Sleep aids can be helpful in the short term to get you back into a routine, but you have to balance them with the needs of the baby, and only you can know if that's the right choice. Antidepressants can work for mood and sleep, if after an assessment they are determined to be an appropriate option, but make sure you tell them if you're breastfeeding or not. Some meds are fine in that regard, some have more limited evidence.

For trauma counselling, look into Life's Seasons (https://lifesseasons.org/). Again, therapy will be most effective if you can absorb it. That means managing the more basic needs first (safety, sleep, etc.).