How should i tell my parents?

I'm a 20 FT college, PT working student. I pay for some bills, not entirely (thanks to help of parents). I have been dating this guy for a few months but within the time frame, we've developed deep feelings. He will be in the navy as of next summer meaning he will get stationed somewhere around the country(I'm a former military brat, I have an idea how things could get). We are beyond content with one another and have even mentioned marriage. We plan on moving in together whenever and wherever he leaves to as he'd be able to support us until I'm able to, too. My parents were raised in a more traditional way so there's stigma around having these plans (as what they consider too soon). It's understandable but this is my life and I have 0 doubts. We don't plan on getting married for a while but just the thought of telling them that I'm moving with him is nerve wracking. My mom has a damaged relationship with her mother do what'd hold her back from one with her daughter? His mom and family are supportive of our relationship + plans. My family likes him and spend time with him, they know we take care of one another. Side note: I'm not pregnant and not immature or childish, everyone just has different dynamics with their parents.