I had a miscarriage

So I'm 17 and I'm in a relationship with my 19 year old lover. He has been going through a lot at his job and home and has been super stressed. On Saturday I had a miscarriage. I didn't even know I was pregnant. The night before I took a negative pregnancy test. I told him and he felt awful (idk why). I took plan b for the third time (in a three month period) and I had also just started taking birth control and so this was a big shock. Any tips for us trying to cope? I'm very traumatized to be honest. And my side note: my parents have no idea about him or that I'm sexually active 😿