Waiting

Hi I'm 28 and started TTC in Jan 14, found out we were expecting in Apr 14. Went to our 12 week scan to find that there was a sac but couldn't see a heart beat. A week later another scan which then found 2 sacs but still no heart beat. Misscarried naturally 21st June ? AF came 26th July so now just a waiting game. No AF yet but not really sure on my cycle so no idea how long to wait before I take a test!!!