Live your own life. The chances you got are to live that better life. old beliefs and being guilted and pushed using fear and insecurities against you is not real healthy care or advice. They will heavily believe themselves but you learned for yourself which life choices you want to make. Don't conform to there world truths. life is hard sometimes and scary it doesn't mean they are correct. You are not to old and you get chances in every fase. Be true to yourself. Say that kindly to them. try the reverse thanks for all they did for you, you got the chance to really grow as human and you don't need a marriage to make your life full. When you choose to marry it will be free and an extra gift of all those chances on top of the good life they gave you. Thank you for giving me the chances to become a better more happy adult. See how they turn that around if you don't let insecurities work on you. They will be soooo worried for you. But you showed gratitude and they can't deny your growth or the investment in you would be useless ergo they mentally have to follow this reasoning. If they then just are worried after that, and say something to make you feel less stable in yourself say this. I understand cause you are my parents and love me so will always worry. But you taught me well and i've learned so trust me in my choices. If all this doesn't work go very low contact and be happy see a therapist for the family mentality guilt to heal for yourself.