Was I pregnant??

So I've been on the Depo shot for about a month now,
and I understand that your periods can become rather irregular.
I never got my period in October, and I got it this month.

It was in more than one way different to what I usually experience.
First I had Brown Discharge [Saturday-Sunday]
Second I started bleeding [Monday- Thursday, present day].

Today I had some really strange clotting, and had some mild cramping.
About 2 hours ago I experienced a mixture of normal tissue,
and some whitish tissue that kind of resembled chewed gum or if you really want to be grossed out, phlegm.
Well, anyway, I thought maybe it was just cervical mucus put into the mix,
but then I had stronger craps, and when I went to the bathroom about 10 minutes ago, the same thing came out of my body,
except it was about 2 inches long, and an inch wide.
It was also whitish, and looked as if it had bubbles in the tissue.
Very awkward.

Either I've just never noticed the awkward color/texture of the lining that is shed monthly,
or something was is up, and I was unaware.