She's still really young to be able to recognize when she needs to go out and to figure out to go to the door. Housebreaking Johann was a somewhat lengthy process, but part of that was him being the first puppy I've had.
Our routine was: to bring him out before eating, after eating, after he'd run around (even for just a minute), after playing. We also had a "schedule" for him....he went out every hour to 2 hours regardless of if we thought he needed to. Once he was 6-7 months old, he would whine/bark to let us know he needed to go out. Even then, we still made sure he went out every 4 hrs regardless.
He got tons of praise and love for going to the bathroom outside. Our neighbors still think we're a little nuts.
Johann has always had water available to him, even at night and when he's in his crate. I don't agree with limiting water and think it can lead to more issues (and health concerns) down the road. But, we only feed him "meals." His dish goes on the floor, and he gets 20 minutes to eat.....if he doesn't eat it, then he waits till his next meal. We did 3 feedings a day until 6 months, now he only gets 2. I think free-feeding as a puppy would make it really hard to housetrain, it was easy to know that Johann pooped right after he ate, and not very often otherwise.
Its hard to not get frustrated. I know my hubby was very frustrated with Johann and felt like he'd never be housebroken. But, around 6 months he was pretty solidly housebroken. He's only had a few accidents that were not his fault at all (i.e. DH hears him whine in the morning, ignores it and take a shower/gets dressed. By then, Johann has peed on the floor). So there is hope and light at the end of the tunnel.
Has she ever been checked for a UTI?