I would think its down to the knee ding and proving . Thee is also quote a lot of salt in the recipe .

Cut down the salt to 1 teaspoon full then gradually as you gat used to less salt in the bread cut it down further.

We use a tablespoon of sunflower oil in the bread that we make . ( for a large loaf ) .

Bread dough is also very susceptible to atmospheric conditions as a result it sometimes does not rise fully.

Try this ... Make the dough and knead it really well , it needs to be smooth and will spring back if you press it , also if you hold up the dough gravity should stretch it rather than it breaking .
Put it in a bowling the side in a coolish place and prove  it overnight .
In the morning , knock it back , share it and leave it for a second rise .

I am sure this will help.

Also the water you add should be warm and not hot , you might have it a little too hot. You might have it a little too warm .

Another thing .. I presume it's the fast action yeast sachet you are using .. Mix this into the flour . Separately from the salt . Then add the other ingredients .
If its a sachet of normal dried yeast rather than fast action you might need to activate it first in a separate bowl ,using the water and some flour. ( can't remember but I think you add the sugar also to this starter ) this can be done the evening before you make the bread . And cuts down a bit on the rising time .
Some of the contestants on the "great British bale off " did this . There was an episode on breads a couple of weeks ago (might still be on NBC iplayer

Hi kye. The loaf I made yesterday was much lighter. Thank you.