HELP meee

AH I feel so crazy. It's been 36 days since my last period ended.. And no signs of my next one starting. I had no period at all in April! I am wondering if I am pregnant. I don't really have any symptoms other than my breasts are a little tender. When can I take an accurate test? I feel like I have missed my period, and I have taken a test but it was defective. ( the other line never showed up next to the plus/minus) ... Help please!