Don't use scales, am I waisting my time?

If you truly believe that measuring/weighing things will take up too much time, would you be willing to weigh/measure for a short period of time at least? What I mean is for several days, weigh and or measure everything. This will allow you to see what a proper portion size/serving size is for what you're eating. Then when you don't have time to measure, you'll still be able to more accurately log what you're actually eating.

I am assuming that while you are logging your food on MFP, you're simply estimating how much you're eating and therefore most likely under estimating the amount of servings you're having and ultimately the amount of calories. So, by weighing and measuring everything, you'll know in the future that "one fistful" of crisps is one serving and "one fistful" of candy is two and a half servings, and you can keep more accurate track of the calories you're actually consuming.