Roxy was exactly the same, We used to get up and let her out in the night to wee every 2 hours or so and extended the time we left her for gradually. She soon went through the night (to be honest I can't remember exactly when, I must have blocked it out!! I would guess at 3 1/2 4 months ish ) but even when she went through the night she was up and awake at 5.30 and wouldnt go back to sleep until she had been fed and played with. What we did was to get up at 5.30 for a bout a week then we just started to extend the time, so the next week it was 5.45 for about 4 days then it was 6.00 etc etc, we made sure she knew she had to settle til at least 7.30. We didn't set an alarm, she was still waking at 5.30 but we didn't get up til the time we decided on, we would ignore any fuss she made until it was time to get up.
This worked really well for us and it didn't take too long for her to settle into a routine. As we didn't go to her when she cried she gave it up! She is 14 months now and sleeps til between 7.30-8.30 depending what time she gets to bed, then she will start to whimper, we go and feed her let her out and then she will go back to sleep til we get up.
We left her to cry right from the first night but always got up to let her out to wee. Its personal choice but we didn't want her to have to sleep with us (she does occasionally for fun! but generally she sleeps in the kitchen) Its quite hard to ignore them when they are so little but once you get a routine going and they get used to it they are fine!