Is it normal?

Okay so I’m 3 almost 4 months postpartum. Gave birth may 4 and got on birth control on June 16. Never been on birth control before getting pregnant. Anyways June 16 I started on the patch. On June 18 I started my period. It lasted about a week. After that I hadn’t had my period. I even taught maybe I was pregnant because I was having some symptoms ( tired/sleeping a lot, heartburn, some nausea) So I took a test that came out negative, about a week later on Friday Aug 14 I started cramping really bad and started my period. So this is TMI but when I wiped on Friday there was this maybe quarter size pice of tissue.. I got a little concerned and looked up pictures of an early miscarriage and I taught maybe I had one. But I wasn’t in any type of pain besides the cramping. So I didn’t seek medical attention. Well ever since Aug 14 I have been spotting which I think is my period? I’ve been cramping all week. This is my first baby and before getting pregnant my period has always only lasted 2-3 says. What should I thing? Should I be concerned? Is it’s just my body trying to adjust to the patch (bc)? Wa sit maybe a miscarriage?