Confused and looking for advice

I am 7 months pp and for the last week I have had on and off blood when I wipe but very light. I have missed my period based on my app but I don’t really know my cycle very well because I am pp but I have had my cycle back since 4 months pp. The light spotting made me think my period was going to start but I am confused why I have been spotting for so long this has never happened before. Do I go buy a pregnancy test? Or is it a normal pp thing? This is my first baby so I am just lost over here. Has anyone else gone through this?