I'm 27 weeks pregnant and have had to previous CS's. In earlier pregnancy I was having quite a lot of pain around the scar, but it has settled. If you are worried about the scar rupturing during pregnancy or even during labor it is very rare and most like would not happen. I had a CS with my first bubs because he was breech. Then I tried for a Vag birth with my second, but it didn't progress. It was probably the scar tissue that stopped it from progressing, but the Dr/Midwifes kept a good eye on what was going on. I ended up having an emergency c-section and was fine. Don't let mine or anyone else's stories scare you, as everyone is different. Talk to your Dr or Midwife, as they know you history and are the only ones that can give you the accurate information.
When I was pregnant with my second I was determined to give birth Vaginally. When you have a CS they check the condition of your uterus ect when they are sewing you up and there should be some sort of report that your dr can access to find this out.