Thank you for sharing this, Verity!
Your story completely documents the frozen, stunned UDIN, and then your sympathetic reaction. You were the heroine here and weren't hopeless when you ran and shouted! That was your brain stem in action, chasing after its chunk. And there was a discharge of energy which you should congratulate yourself for. Otherwise it might have given you ((Digestive - Tonsils|throat)) trouble or affected ((Endocrine - Thyroid - Follicular Epithelium|thyroid)) hormones, who knows?
What happened next were following conflicts that created the self-devaluation and negative beliefs, which were immobilizing and "depressive", in that thought you better had controlled yourself. We are such herd animals that we want to adapt to what "they all do", and "they" were rather frozen or distanced! But health lies in that you attend to yourself and let it out, while being open for co-regulation with others in safety. Some debriefing with your mother might have been helpful.
While the sensory cues seem to still be meaningful to keep you safe, the belief "Why would someone go out of their way for me?" could be reviewed. Yes why? If your "Chunk mind" would speak and you absolutely NEEDED to get through to your child or your treasure because... - then they would wouldn't they?