I'd presonally prefer eating avocadoes over seeds if I was looking for fat. Although a whole avocado is a whopping 30 grams of fat, you need to make sure you are getting a lot of calories, or just eat a few slices.
Can you try inputting your daily intake on
www.fitday.com and then telling us your ratio? I think you will be quite surprised that you are getting fat in your diet. If you aren't eating any overt fat, like nuts, seeds, avocado, etc. then you are probably getting somewhere between 6-8% which is perfect, as the healthiest amount is 10% and under.
And to many people's suprise and astonishment, the BEST fat (yes that "good" fat) is found in all WHOLE FRESH plant foods, in perfect amounts. People don't realize that there is fat in greens and bananas and stuff like that, it's low but it's in there.