Please help. I think I just had a miscairrage. Im not sure an kinda scared?

Okay first of ive been on birth control for 3 months I had break through bleeding and then it stopped a while ago. But for the last 2 or 3 days i have been having some spotting. And today me and my boyfriend had and I started to bleed really bad so bad it came through my jeans but then when i went to the bathroom something came out of me it was red and about the size of the palm of my hand or a little smaller and im having light cramps and feel a little woozy. But I had my period last month what could it be im not even on my week of pills to start my period starts around the 18th or 19th what do you think??