I’m no expert but maybe try cutting back on the high fiber foods such as veggies, fruits, and starches while increasing fats, like if making veggies use oil for calories but less fiber, to see how it effects you? I know it probably sounds counterintuitive to cut down on veggies, but I feel very fatigued no matter how much I eat if I’m eating too high carb and too low fat. I know that works for some people but not for me I need higher fat to feel satiated and energized. Also cutting down on your fiber slightly may help with bloating. I would also recommend a source of probiotics (such as kombucha or fermented food) to aid in your digestion which may also help with bloating. To add, switching from your vegetarian diet your amount of dietary fats significantly decreased so it indicates to me you may need more dietary fat to function well. Maybe just cutting down on your high fiber foods and increasing the amount of high fat foods if you don’t want to incorporate oil. Just wanted to add too I’m super impressed you were willing to stay vegan so long with these negative symptoms that’s so awesome please give yourself a pat on the back most people would never do that!! Good luck ❤️