How old is your baby? Keep in mind that for the 1st year of life, a baby needs to be fed on demand... this is per our Pediatrician as well.
Next, are you producing enough milk? If a baby is not getting enough intake... they will cry/not be happy/always be hungry.
Next, is your baby latching on properly? Is the entire nipple/areola in her mouth? Do you see your baby swallowing? If a baby is not latching on properly, they will not be getting enough intake either.. .and will not be satisfied and will be hungry.
Next, does you baby have gas? This also makes them uncomfortable.
Also, at certain growth periods/spurts, a baby even "cluster feeds" which means they even feed every hour.. .and need to. If not getting enough intake, they will be hungry because their intake is NOT keeping up with their growing and caloric/nutritional needs.
Have you tried a sleep sack for your baby? Sometimes this helps and makes them feel cozier.
If your baby is older, not a newborn, you could try a pacifier if you are not against it.
If she is a young baby or newborn, I would not have her cry it out....
I've had a couple of friends whose babies were like that... and it turned out that the baby was basically always hungry and not getting enough intake... either because of improper latching (by the baby) or them not producing enough milk.
Good luck,
Susan