Phase 1: Ceiling Crawling
Gohma will crawl on the ceiling. Wait for her eye to open and turn red. Use your Fairy Slingshot to shoot her eye, stunning her. When she falls, attack her eye with your Kokiri Sword. Repeat this process.
Phase 2: Egg Laying
After taking some damage, Gohma will start laying eggs. Defeat the Gohma Larva quickly with your sword or Slingshot. Continue to stun and attack her eye as in Phase 1. Keep moving to avoid her attacks and the larva. A few cycles should be enough to defeat her.