Membranes....

So today is currently Tuesday. I spent late Sunday night/early Monday morning at my women’s birthing center because I thought my water broke(I’m 29w4d) they said that it wasn’t my fluid and it wasn’t pee. It was the fluid between my placenta and uterus. Is that my membranes...? And they said I was very soft. How long after loosing membranes has anyone went into labor..? They did a ultrasound and everything looks great but they said they won’t be able to stop labor because she’s into birthing position. I’m really freaked out. This is my third baby.