Baby refusing to nap longer than 30 mins

I'm going crazy here. My daughter refuses to nap longer than 30 mins. I used to offer a 2nd nap but lately she refuses to take it. If I move her bedtime early she will treat bedtime as a nap and then won't sleep til midnight. If I keep her regular bedtime she's OK at first but then wakes at 2am until 5am. Please send help I'm exhausted