The general recommendation for fiber is 25 g per day for women, 30 for men.
My fiber usually comes from apples, pears, strawberries, other fruits and vegetables, nuts (though that's not a low cal option) and whole wheat bread/crackers/tortillas. There are high fiber options for these out there, if you look and read the wrappers. Beans and legumes also have a lot of fiber. If I'm low for the day, I'll have some fiber cereal or a fiber bar, though those aren't my preferred options because of the sugar and additives.
And now that you don't have to be perfect, you can be good.