To quote Austin Powers "..things got weird, didn't they...?"
Family dynamics get very weird when we live with our parents--no matter the age that you do. You're 5 again. Instantly. AND, since you're not really 5, you are seeing your parents as people, because you see how they treat someone that you love very much.
All I can tell you is to make the best of it. Can you get married? I know, I know...but it will put things "right" in the minds of your mom & dad. If you can't afford your own place, get the notion of "saving for a wedding" out of your head. Just do it. Simple & small. Right away.
Your fiance needs to get work--ANY work in order to take advantage of this time when you CAN save money for your own place. Deliver pizza, wash cars, work at Wendy's--WHATEVER! This is valuable, rent-free living and NOW is when you need to save!