Have you tried 24 hour yogurt? I make it with aseptic packaged soy milk, I am lactose and casein sensitive (casein is a milk protein that the Lactaid supplement does not help you digest).
It is so easy to make the 24 hr yogurt if you use aspetic packaged plant based milk, you just sprinkle the probiotic into the carton opening and shake, then add it to sterilized jars in your Instant Pot or incubator and let it ferment. The plant based milk you choose cannot have any additives in it, there are a lot of recipes on the internet if you are interested.
I have loose stool from a shortened small intestine (complicated appendix sx) and the yogurt really helps firm things up. You can research what gut bacteria would be beneficial to your issues and use them in the soymilk. I did not purchase any special starter, just used the probiotic capsules I had on hand.
Here is a link to more information on it: https://healthygut.com/scd-legal-yogurt-is-the-difference-maker-dont-eat-it-at-your-own-risk/
Your sensitivity to vegetable juice makes me think you might have a FODMAP issue. FODMAPS are fermentable carbs, fructose is one of the biggies as it is in a lot of fruits and vegetables. A Dietician told me that most Adults have fructose issues as they age. Look up Monash University, they developed a FODMAP program and have a great app that helps you figure out portion sizes and what carbs are contained within a specific food.
Best of luck on your journey!!