Could this be a miscarriage?

I recently started the depo shot for birth control on 8/29 but me and my boyfriend have been having sex (with condoms) since about 5 months ago none of them ever showed any signs of breaking but we started not using condoms once I got on the shot. For the first month on the shot I missed my period and then this month my "period" started with spotting for a week and then got heavier and today this came out after having agonizing cramps. I have never had any cramps on my period and its never been this heavy also it's been going on for 13 days now. I also usually never pass blood clots for once and this sack thing was the size of my palm maybe a bit bigger

Is there any way I can check for sure that it wasn't?