I totally agree that a consult would be the ideal thing for you to amp up your progress and answer questions specific to your particular needs. I encourage you to do that and/or attend a FoodnSport event.
In the meantime here are some thoughts that came to my non-expert lay-person mind for you to consider to see if they ring true to you and to work into whatever experiments you are trying, or totally discard at will, hehe.
Have you heard of melon belly? Some people get this when eating melons, and sometimes it's felt in the back instead of the belly. I don't get it personally. Darrel gets a pain in his back when he has juicy fruit in the morning after having eaten non-80/10/10 style the day or few before. It seems to me like it's his peristalsis suddenly kicking in when it was previously sluggish from the other foods, which feels a bit like a cramp if I remember correctly. He doesn't get it if he's been eating 80/10/10 style for a while though, and he doesn't get it from the sweeter fruits it's from the juicy ones.
From some of your other descriptions I'd think it had more to do with volume than sugar as you seem to be having smoothies rather than drinking strained juices, right? If you are having strained juices you could have sugar issues, however I have not heard of this symptom as being one related to blood sugar issues. Straining juices removes the fibers that regulate sugar uptake and your elimination of the solids later on through peristalsis so it makes people more likely to have blood sugar issues than they would if eating the foods whole with the fibers like you would do if making a smoothie with the fruit instead.
Another reason I'd think it wasn't sugar and more of a volume issue has to do with what you said here:
Before 811 I would eat when my stomach growled followed by a feeling of weakness and shakiness. This happened about every 2 hours. Now on 811 I don't get these feelings and sometimes it's hard for me to tell when I'm hungry.
The description of how you needed to eat every couple of hours before 80/10/10 is similar to the descriptions I'm familiar with of blood sugar issues. The fact that you are not experiencing this now seems to indicate that you are having less issues with sugar imbalances than you were before.
I personally find it more difficult to get enough calories with bananas if I make them into a smoothie because of the extra volume the water takes up. I know that a lot of people find it easier to drink smoothies and will get more bananas in that way, but for me it's a volume thing. I find it quite easy to just eat a bunch of bananas and if I find I don't like the bananas enough to eat enough calories I'll add dates to the smoothie in order to make up for the calories lost in my ability to drink enough volume with the water.
If dates blended with water is giving you issues, have you tried using less water so it's less volume? Also, have you tried adding in celery or greens to add more fiber to help with sugar regulation?
I personally don't have a sweet tooth, hehe, yeah funny that I'm eating primarily fruit, eh? Anyway, I find it difficult to eat dates alone because they are so sweet, and I don't like things that sweet, so I always eat them with either apple or celery chaser bites in order to even it out. I find apples are not a good calorie source alone, so always eat them with dates, so it works out in both directions that way, hehe. Perhaps those things will help you as well.