Menstural cycle. Or not. please help me.

My periods date are as follows: 21st Dec 2016 25th Jan 2017 7th March 2017. Since then, I have not been on my periods. I am worried. And from past few days, there is something blackish coming out of my vagina with sticky nature. Today, I found out that a light red colour water type was coming with just few drops. I thought I'm on periods and told my mom. I was a bit happy after all these days, I was in periods. But it's been hours since blood has come out of my body. My pad is new: it is without any blood. When I went to bathroom, I did my work and at the end, I saw two to three drops of light blood (I think, it was not clearer). I am very much tensed. I still don't know whether I'm in periods or not. Please help me.