How to stop losing as D.VA when defending?

I'm a pretty new player, I've been playing a lot of D.VA lately to try to learn her and I keep losing whenever I'm playing on defence. I feel like it's really easy to play dive on attack since you just have to cause a lot of chaos and destabilize the enemy team, whereas on defence it's really hard for me not to just die immediately when diving the enemy team. I was wondering if you could suggest some resources on how to play D.VA, or just dive in general, specifically when defending.