Your armor and accessories look very good to me. It is a pretty optimal set for movement and healing.
I would personally replace the Worm Scarf with a different accessory that deals more damage or gives a different type of benefit since defense doesn't mean a lot on Master Mode. But that is up to you. It is fine to have some damage reduction from the Worm Scarf.
If you haven't yet, I would recommend ensuring you've eaten 20 Life Fruit to ensure you have 500 HP. Based on your current health bar, I can't tell if you've eaten all the possible life fruit or not to have 500 HP.
Megashark should also be a fair weapon to use against Plantera. If that doesn't work, the Shadowflame weapons can also still be effective against Plantera.