Congratulations! Do NOT let negative family members spoil your excitemement and happiness. You are an adult and made an adult decision and if they cannot support you in it, then that's a shame on them. Sometimes you just have to do what you have to do. This is your life. Your parents are probably concerned that you are entering a legal contract with a person to whom you are not married. It gets super sticky if one of you wants out of the relationship. Still, it is your decision to make.
I am moving to Eugene, OR sometime in the next 1-2 years and I signed a construction contract today. Yes, it can be scary to make a big change. Do it anyway. Life is too short to not be happy. I am excited for you. Enjoy your new home and life together.
You might want to get rain boots and an umbrella . . .