Amniotic fluid vs pee

How can you tell the difference between amniotic fluid and peeing yourself? I asked my dr yesterday when I had my appointment about fluid that's been trickling down my legs randomly for the last three days. She said that it's probably the baby hitting my bladder and it just comes out. She did tell me though if I keep experiencing it that I need to call back. Well how can I tell the difference between the two in order to call back?? With amniotic fluid, would there be a little blood or minor contractions?