Miscarriage or period???

So today I started having mild cramps. I thought I was finally getting my period after being late. (I took 3 pregnancy tests and they all came back negative). I finally got home and went to put a tampon in and when I wiped there was a little blood but there was also a clear sac/tissue looking thing. I don’t know what to think of it’s normal or if I’m having a miscarriage