TW: Miscarriage

I’m 17 and I recently had a miscarriage. My boyfriend was sad the first day or two but now he acts like it never happened. I can’t stop thinking about it but every time I try to talk to my boyfriend about it I feel like I just upset him. I really don’t know what to do to stop thinking about the child I would’ve had 24/7.. Does anyone have any advice for dealing with this mentally? :(