Well, within reason, I think it is wise to let baby puppies eat when they are hungry. Their little bodies are doing an awful lot of growing at that age. Puppies may be notorious for being picky eaters - but that tends to be in stages
When they're in the middle of a growth spurt, they're often ravenous - the uninterested periods follow and coincide with periods of lesser or no growth.
At 8 weeks, I'd say three meals a day is a minimum and I prefer to be giving them a couple of light snacks as well.
In short, I think it wouldn't hurt to let your girl have a bit more food, or to split her food into a greater number of meals. Obviously, that advice has to be taken within reason as it isn't good for puppies to be overweight. However, if she's just a normal healthy weight, then I'd go with what her stomach is telling you and up her food intake/frequency a little