i really relate to your struggles too! I'm finding it hard also but each time i fail I'm learning a lesson as to how to approach it differently next time.
I've learned that the fast that worked best for me was to begin the night before from 6pm onwards to fast~ Then i had a warm toasted pita bread (half of a big one), with a hot drink (i had Chai Tea) before bed. (if i'm too hungry then i dont' sleep) then the next day i had mostly liquids like tea,coffee, 1/2 lemon in water, etc. I tried bread early in the day before and it knocked me out so thats not for me. :lol.
Then later on in the day..closer to the time i was going to break the fast..i think i had some more of that pita bread (1/2 one).
This example is probably not the best one but i think i can at least try to get to grips with.
I failed miserably the last day i tried to fast, i had bread in the AM..but i was painting and soon i felt those familiar symptoms of hypoglycemia..(i'm not diabetic though or anything)~so then i had some bread to keep me going (which again made me super drained and tired) .
i usually need to have some kind of protein in my meals to prevent this. This is why i'm better off with little/no bread on my fast day.
This is my new discovery anyways and the next time i'll do it better. Hopefully i've have some good news to report soon.
Then I'll take smaller steps to have just water alone as Our Lady says to do.
i'll say a prayer you find the best way for you to fast too!.