I'm not sure which, exactly, are the top 8 (I have a good idea).
We don't do smoothies that much, but I think the ideas you've had so far are good. I think a can of coconut milk like you make curry with would be better (fattier) than the coconut milk they sell as a milk alternative. Just put half a can in the blender and add whatever frozen or fresh fruit you like to eat -- bananas tend to make sweet, creamy, yummy smoothies, but some people don't tolerate them well. Berries are awesome, I also peel and core apples and pears for smoothies. Veggies, especially greens can be a great addition. Really, just throw some fruit and your milk substitute in there and blend it up. Add more stuff if you need to. Add a little maple syrup if it's too tart.
Avocados and guacamole if you have time to make it are so great for breastfeeding. Also, my ds won't eat avocado, but if I make guac he eats it with a spoon!
Refried beans with lots of olive oil are super delicious and filling. You're probably off corn, but you can just eat them, or top them off like a taco salad with lettuce, grated carrot, avocado or guacamole, olives, etc.
Can you eat nuts? A handful of nuts a few times a day can really help with calories.
Potatoes? They can really help you feel good and full -- sautee a bunch of onions and mushrooms (protein and minerals!) in olive oil and have them over potato with other veggies.
Oooh! We make this tahini mushroom gravy that is awesome over millet. Steam the millet just like rice -- it is good to roast it (stirring constantly) in the dry pan until it is aromatic before adding the water to help get rid of the bitterness. Soaking might help with that too. For the gravy, sautee onions and mushrooms in olive oil, add minced garlic, season with salt, put some tahini in a jar with water (probably half and half?) and shake it until smooth -- you can do this in a blender if you prefer. Pour the tahini into the pan and cook with veggies for a few. Eat it over the millet with steamed veggies.
And as a pp said, eat a lot of what you can eat, and just keep eating!