Another miscarriage!

Well this will be my third miscarriage! At 30 I had a D&C done at 12 weeks, baby had no heartbeat and stopped growing at around 6 weeks... Now 4 years later at 34 and had a chemical pregnancy last month and this month pregnant and have been miscarrying for 4 days now, (I'm trying to do this naturally) this is very hard and very hopeless! I have one beautiful 7 year old baby girl, with no problems at the age of 27. I just don't understand... Does anyone know how long till I should expect my period when this is done?