Am I out for this month?

Hello, Ive been TTC for over a year now. We were successful this past March but miscarried, and have been trying ever since. My cycles are VERY regular! And I've been experiencing a lot of symptoms! I'm suppose to start today, but nothing yet, and yesterday I thought I have a very faint positive, then this morning, a for sure negative... Is there still a chance I could be pregnant? How long should I wait to re test?