Having no family left at 26, no siblings

Im currently in the process of loosing my mom to cancer after her 14 year cancer battle. My dad abandoned me when I was 12, I have no siblings and no other family. How does one go trough the world without any relatives or support network? I dont think I can handle this, Im in therapy but it doesn’t help much. I dont know anyone who had the same experience. Im currently in the mids of my med school, i would be finished in 2 years, but I dont think I can push through that all alone. Did anyone have the same experience or suggestions?