Essential fatty acids are mainly omega-3 oil and since we already consume too much omega-6 in today's world, it's basically known as fish liver oil but you may also find it in following oils: Flax seed oil, evening primrose oil, borage oil, olive oil (much omega-6), black current seed oil.
Amino acids you can find in meats, fish and poultry while in candida diet but supplementing the additional part is better than overeating meat.
The most important amino acid for leaky gut is probably L-glutamine, a product with L-glutamine usually contains other amino acids aswell.
I think too much onion will not make a difference, but moderately eating "a lot" of onions is enough.
Maybe it's vital to postpone antifungals, even reduce garlic to one clove a day since it's detrimental against the friendly flora in the bowels, after three weeks of proper supplement for the gut increase dose of garlic to two or three cloves a day, two or three weeks after that introduce antifungals (preferrably Grapefruit-Seed-Extract
or Oregano oil) and probiotics.
I were in your position exactly ten months ago or so and i would say that if i had all the answers in my hand then which i have now i'd been cured much sooner.
I've found olive leaf extract to be extremely helpful for healing the gut and fighting off the yeast at the same time but it is at the same time extremely destructive against probiotics so i would only suggest it to experienced users.
Iron deficiency is connected with leaky gut since candida depresses the metabolism in your gut which makes iron run low and i would say to introduce it at some point after two months or so.
Just taking simple steps in the beginning is the best thing to do, leaky gut companied with candida is much more difficult than just leaky gut.