Hey Shilding! If all you are putting with the spinach is some lemon, sea salt and garlic, you can have a whole lot of spinach. The salt could be problematic as it can cause you to retain water, so maybe go lightly on it. Most folks don't weigh their veggies and you should find that you are getting full before you can eat a huge amount. The veggies have so few calories that it shouldn't be necessary to weigh them. If you eat a bunch during the day, you technically should skip them at your meal.
Re: the scale, remember when Dr. S. wrote P & I it was many years ago! Today's kitchen scales are much more accurate than in the 1950's.
Any tea that doesn't have added sugar or starch in it is fine to drink. Same with coffee. The cooking spray is probably loaded with chemicals and not good for you. If you use a little water or broth when cooking, you shouldn't need the spray.
Good luck, hope you have great success and keep us posted!