@Liz_McDaniel Good that you set an achievable goal and will then re-evaluate. If you feel weak, I would suggest a ReFeed to prep your body for a longer fast.
I did a 4, 5, 7 and then a 40 day water fast with ReFeeds between each fast. By doing it this way, I didn’t have a problem except after my 7 day. I went through a period of 4 consecutive days I couldn’t get beyond Day 1. At first, I thought it was a matter of willpower then I realized it was actually my body screaming at me it needed a break as by that time I had been on my treatment protocol for 2 1/2 months. I did a 9 day ReFeed and then tackled the 40 day which I completed successfully on 11/30 last year.
Hope this helps.