im 17..idk what to do..

I'm 17 and I just had my 4th miscarriage.. All of my pregnancies have never made it past 8 weeks... my first two I was 14 (it was young yes completely different story, please no hate I'm dealing with enough) and I assumed it was because I was young, but in the last year I miscarried twice. I'm beginning to think there's something wrong with me.. I can't talk to anyone but my bf about this. My parents would shit a brick if they knew about half the shit I've been through.. I don't know what to do.. can anyone give me some advice as to why this may be happening?.. or how do I cope...