I don't believe turning lag comp off will suddenly make the fight easier. It's dragonfly that's weird.
You haven't really given much info on what you've tried or what you're doing so I'm going to assume a lot of things. See because dragonfly moves while attacking it changes how you fight her. This means that following any "constantly hit 6 times and then dodge" advice should go out the window because it's not always true.
Think of when dragonfly attacks as a timer that goes off. Getting 6 hits requires you to be incredibly precise with this timer and even something as simple as getting hit will make dodging impossible as you get stunlocked for like half a second after getting hit. In other words, you should change how many times you attack dragonfly depending on whether or not you got hit.
If you get hit while on top of dragonfly, its safe to go for 7 hits before dodging.
If you get hit while almost out of her range. Go for 5.
If you don't get hit then you can easily get 6 consistently. Its when dragonfly attacks you that I'm guessing your timing get's thrown off. Of course if your not on a road (or don't have some other speed boost) go for 5 because you won't be able to do 6 without the extra speed