Egg whites must be at room temperature.
The water must be boiling.
Do not add excessive water. If needed, at in only 1/2 tbsp at a time if it's too dry.
Weight everything using weighing device. I use a device which gives me up to 0.01g sentivity.
Flaxmeal must be grounded to fine powder form so that it can absorb water efficiently.
Psyllium husk MUST NOT be too fine as it will reduce its ability to absorb water.
Instant yeast is optional. It does not help to rise the bread but only for bread flavour.
Do not use a cake tin which is too small for it to capture heat and rise evenly.
Do not cut the bread while it is still hot as the bread will shrunk and collapse which end up a cakey bottom.
Let it cool in the oven with the oven door opened will prevent the bread shrunk due to temperature shock.