Here's what we do with the child I work with - 1/4 juice to 3/4 water. He likes it WAY better than water but it doesn't have much sugar. He drinks LOT and pees a LOT. (He's 5 now but I've been working with him since he was 3.)
The other day he had peed twice in 2 1/2 hours and then we were working on oral/motor therapy (he's got autism) and he peed while we were working! He's only had 1 pee accident since I potty trained him over a year ago. I thought, what's up! THen I realized that he'd had a lot of water/juice, and then we were playing with wet washcloths and ice cubes. I think that did it and he couldn't help it. Because then when I took him in the bathroom afterwards, he sat and peed some more! YIPES!
Plus, when we potty trained him, he peed ALL the time, sometimes more often than your daughter. She's probably getting used to the "I have to pee" sensation and honoring it each time. After a few more weeks, she'll go longer and get used to how it feels when she actually *needs* to go.
I wouldn't worry about a physical problem if there's a lot coming out. I'd only worry if it was a tiny bit and she felt like she HAD to pee - urgency with uncomfortableness soon after she'd just peed.
I think with extra water with a bit of juice, or a bit of a vitamin powder like Emergen-C for taste (and vitamins!) she'll be fine.
Early intervention specialist and parent consultant since 2002.