Was this a miscarriage?

In February on 2016, I had this happen to me. If it were a miscarriage, I wasn't aware of the pregnancy at the time. I passed about 18 clots this size and was in some pain for two days. Then it stopped. I have normal periods and this had never happened before nor had it happened since. It started on a Friday night, and I went to the school clinic the following Monday. They said it "could have been a miscarriage" but they would never really know, since it wasn't a known pregnancy.

Now I am 8 weeks along in a healthy pregnancy but my OB wants me to report if I've had a previous miscarriage. I didn't have these pictures on my new phone at the appointment, but will show him next time. I told him what had happened in 2016.

Long story short, does this sound / look like an off freak heavy period? Or should I consider myself someone who has had a previous miscarriage?

So sorry for the images. Thanks.