What Causes Heavy Periods With Passing Of Clots And Tissue?

Hi, i am 25 years old and i have 2 babies, i had my tubes tied after the second one but i started feeling pregnancy symptoms last week, morning sickness, tenderness in my breast ect. But yesterday i got what appeared to be my period. It is heavier than usual and today i passed a massive size clot of blood. Two hours later i had tissue discharged as well as a lot of tiny clots of blood. Does this mean that i was pregnant and had a misscaridge???