As Darryl says many of us have been working with this for many years and it is not easy to do this on your own. I found that it began to make far more sense when I was actually able to get into a planning lesson with a teacher as they were able to fill in the ‘topic’ and ‘knowledge’ side of it that I really did not have a clue about. This obviously is not possible for you at the moment but hopefully it will come eventually. Gaining as much knowledge about this process now is a good way forward until things begin to get back to ‘normal’.
So be gentle with yourself and getting to grips with FOSIL like you are is the best way to do it. I too have been working with this since 2013 and even now I have a conversation and something else slots into place. It is only by talking, asking questions and sharing our thoughts that is going to make this any easier.
One of the things that the workbooks don’t focus on is the skills framework and I found when I was struggling that this was where I needed to head to see where my skill set fitted into an inquiry so it might be worth going back to that to see if it helps too.
When I was working at SLS Guernsey I created individual documents based on the skills framework that broke it down year by year which I found help me understand where I could support an individual inquiry. Here is the link to the secondary document and also the primary one too.