I highly recommend trying the three hourly feeding routine during the day (feed/play/sleep). Your baby needs one big block of sleep a day so soon she will get the idea to do that big sleep at night. Start a nightly routine too so she knows it is time for her big sleep. Our nightly routine ends with a bath then bed, I then give a dream feed at 9:30pm where the lights are low and there is no talking or playtime, just straight back to bed. It really does work, I have done this with both my boys with great success.

I know it makes you feel guilty waking them in the day for a feed, but soon she will fall into a pattern and wake naturally by herself and then sleep longer at night for you.

Best of luck