You have already received some excellent information... I just want to point out the facts of the breast that many people do not know.
Breasts are glands, not bladders: that means they produce milk continuously (there is not such thing as an empty breast) and in response to hormone fluctuations and physical stimuli. This means that the more often you nurse, the more milk you will make. Just like saliva: the more often you eat, the more saliva you produce. Has anyone suggested pumping saliva if you eat more frequently than usual 'to make sure you have enough'? I haven't.
The texture, density and sensations in your breasts are also not indicative of the amount of milk you are making. There are several cases of breastmilk known to be present after death... it's part of your blood supply and you'll 'run out' of both at the same time if you bleed to death, but otherwise you won't 'run out' of milk anymore than you 'run out' of urine.
If your baby is needing to nurse more frequently, it may have a lot or nothing at all to do with her current growth, hunger or dental pain. Teething increases desire to nurse for lots of kids, because the suction pulls their gums away from their nasty sharp teeth, giving considerable relief. She may be anxious about changes in her routine or live, or just growing faster than she had been.
If you don't know her exact calorie needs, you certainly can't determine when she's 'had enough' anymore than anyone weighing you and looking at you can tell when you're hungry or full.
Oh, and suction alone is not how babies get milk out of breasts, which is why many women find suction a poor method of expressing milk. It is actually the jaw action of the baby, not the suction, that makes the let down occur.