Advice, please please PLEASE.

If I am 6 or 7 days PO, when do I test? AF is not due until the 11th or the 12th and I took a test tonight which resulted in a BFN and I got so disappointed. I understand it's early, but after just having a miscarriage... All I want is that BFP. My siblings keep announcing their pregnant and it is literally tearing me to shreds that I can not conceive. I felt like this month was the month, but I don't want to get my hopes up. When should I test and with what brand of test? Please help!