hit a weird bug initially, got to the point where it asked how much water I drank-- I answered "5", and then it reverted to telling me it'll never put me on a diet
If you haven't, I'd check out some other popular chat bots for their UX. Ex.: Woebot https://www.facebook.com/drwoebot/
Having buttons for things like "continue", "go on" or "not right now" is something I took for granted. No need to have me type it if there's a limited set of acceptable responses.