I have not tried anything herbal for the gastroparesis but they do have a good acidofilis that I really like, it is called pearls, they are very small and easy to take, besided gastroparesis (non diabetic) that comes and goes I have esophageal spasms, so small pills are best for me, but I also did feel better taking it. Erythromicin did not work well for me, It gives me ulcers, so I am left with reglan. I only take it when I absolutely have to because I get the side effects of twitching and tongue thrust, not fun.
You might want to look into the herb Shatavari, which is suggested to work in the same way as Domperidone. In addition, check on acupuncture which uses techniques that gave rise to the 'basis' of the gastric pacemaker.
There are some herbal solultions (Segratax, Gastrotab, and Astratin) that claim to help with the condition. I have no experience with them and haven't spoken with anyone who has tried them however. But please be careful and fully check out any product you take that suggests it's herbal or 'natural.' There's really no such thing as 'natural.' ALL drugs are based on 'twigs, nuts, bark, grass, leaves, etc'., that have been used for centuries by populations until some drug company extracted the component that seems to cause the desired effect, popped it onto pill form and marketed it. Natural doesn't mean safe - it's a sales tactic.
Welcome to the gastroenterology community! I tried a couple things that used ginger or peppermint, but none of them helped me.