I read somewhere that sunflower seeds are the lowest in calories. Look, I face the same problem, and I try to remind myself that “too much of a good thing can be bad” daily! I could easily eat a couple of avocados, a couple of servings of almonds, coconut oil, chia and sunflower seeds in my smoothie, more avocado and more almonds in a single day - I love those good fats.
I am not entirely sure of the fat/cal content in most nuts and seeds, and what is better than what. I basically just try to limit how much I eat. For example, if I have 1/4 of an avocado in my breakfast meal, I will have a little more fat to play around with later in the day. If I was to eat 1/2 an avocado, I would have a tiny handful of almonds later in the day and nothing else. I hope this is making sense.
I have recently started to use coconut oil, maybe every third day or so. I try to scatter those fatty foods around, especially coconut oil as I am worried about putting on weight. Adding seeds to salads can become a bit of a habit, so also try to fight that so you are able to have almonds or walnuts as snacks. Good luck and happy eating!