How do you start liking yourself? And how did you learn how to trust?

Growing up with my single NC mum, who constantly put me down for my looks and behaviour and for not being perfect, I feel extremely insecure about dating and men. Having been bullied during 9 years of school (and having the NM blame me and my weight for it as well) certainly didn't help. I've never had a boyfriend at an age 35+ and I struggle with insecurities related to my weight and looks. In addition, I'm probably also afraid to engage in a relationship as closeness in the past has always been related to pain, unexpected criticism, embarrassment, sense of failure, sense of being under attack etc. For those of you who have been able to move on or accept your past - what did you do to start liking yourself? How did you accept your looks? And what were your steps toward trusting a partner? I'd love to hear concrete tips and advice that could help me move forward. Thanks a lot!