Hi Anna
I was in a similar situation to you with my first two labours being induced , I also was booked into a birthing centre for my third. I was panicking as my labours are very short with my first being 4 hrs and my second being 40 minutes.

I was overdue at home when my waters broke for my third, well they didnt gush they just sort of started to leak, i would just get little gushes at a time, after several of these i called the hospital and went in. I was not having any contractions at the time, i was monitored for a while and was about to get sent home when all of a sudden i went into full swing labour, my DS was born in 55 minutes.

Dont stress to much, you will know when its time. If your waters break and u r worried try to get closer to the hospital, plus dont forget you can call in and get checked or monitored like i did at any time.