Is it normal???

I gave birth June 7 2015 by cesarean didn't bleed heavy only spotted and by June 12th it was over. My boyfriend and I have a very active sex life and we haven't used any methods of protection my issue is that I haven't started a period cycle yet and now I'm beginning to get nervous... I've spotted once cramped a very little bit but that's all I was told it takes months for your cycle to get back normal but shouldn't there be something? I've taken a pregnancy test and it came back negative but with my first I took four one every week before I got a positive with my 5th . Should I be concerned? Should I schedule blood work to be sure or am I just over reacting?