Tissue came out during period?

Kristy • Married the love of my life🤵🏻👰🏻4/21/18. Lost our angel baby at 11 weeks👼🏻 12/6/18. Had my rainbow baby boy👶🏻 3/27/20. Lost our 2nd angel baby boy at 21W3D 6/3/2022 👼🏻. Pregnant with rainbow baby #2.

So on the second day of my period, my cramps became more intense and I started bleeding heavier. Not too surprising because the second day is usually the worst for me. But around 8pm, a piece of tissue came out. I immediately freaked out because the only other time that happened to me is when I had a miscarriage. (My husband and I have been trying again and I have taken pregnancy tests before my period came. They all came back negative). My sister-in-law is an RN with experience in fertility. I showed her a pic and she told me it was a piece of white tissue from my uterine lining and it’s nothing to worry about. I’ve had issues with spotting since April and I’m hoping that this was the cause of it. Has anyone had anything like this before?