How can I tell when I’m having a miscarriage ?

Alexis • 3 year old Chloe💖 11/15/15 & Jacob 💙 3-5-19

I’ve been told I have a subchorionic hemorrhage. This is all new to me, I’ve had 2 previous pregnancy where I never bled. I’ve already been to the ER twice because my bleeding got heavier, and I was still pregnant. I just drove for an hour and when I got out the car my pants were soaked with blood. When I went to the bathroom I passed about 4 decent size clots ( sorry tmi). I’m not sure if this is normal for a subchorionic hemorrhage, or am I having a miscarriage? I don’t want to keep going to the ER for no reason.