2 miscarriages😔

So I had my son at 17 and he is now 4 I had no problems what so all during that pregnancy and now me and my bf are trying to have our own baby since he is basically the dad to my son now and we have had two miscarriages😔 has anyone had this happen and still have a healthy baby? My docter is doing a lot of blood work and everything so far is fine but Idk what's wrong with me😔