You've been extremely unlucky - while no method is perfect, the implant is staggeringly effective in preventing pregnancy. While less than 1 in 100 women will get pregnant when using the combined pill correctly, the figure is less than 1 in 1,000 over three years for the implant: that's better than having a sterilisation op.
And then to have a miscarriage, ouch. This will be something you're unlikely to ever forget, but miscarriages are very common. Usually, that's at a very early stage, so it may not be recognised as such but it's estimated that about one in four pregnancies end in one. That's a lot of women who've had it happen.
Do you know about the Miscarriage Association?
Now that you've had a pregnancy, what do you and your partner want to do about having another one? Try to have or try to avoid or see what happens?