My foster dad's asked if I wanted to be adopted..

I've been in the foster system for 7 years and I have been with this couple who are gay for a year and a half. Today they asked if I wanted to be adopted. I age out of the system in 14 months, so is it really worth it. I love them and they have treated me amazing. I guess maybe I'm more worried about accepting it because when good things happen to me something bad always happens. I can't get too happy because if I do something terrible will happen. If I go for the adoption I feel like something bad will happen because I let myself get too happy. I know I sound stupid but I'm scared. I have a hard time accepting love, and I just don't want to mess up what I already have.