Birth Control Problems

Okay well, I've been taking for 4 months now with no period what so ever! Never missed day! 
- couple days I experienced spotting for three days. It was brown blood like it was old. 
I don't think I ovulated at all past the 4 months. Is that normal? I know when I ovulate because I will get a clear haunt blob that shows up in my panties and yes, I get every this month. 
P.s. I take gildess birth control.  It gives 3 rows with 7 pills in each row. The fourth row is when my period is suppose to start. 
Should I stop taking it and get a different type of bc? Should I keep taking it?