Implanon and Pregnancy Risk After Condom Failure

Question
I've been on the Implanon Implant for 2 weeks and 3 days, (i got it fitted at 9.30am on a thursday), and 3 days ago me and my boyfriend had sex, but the condom fully split in half and he ejaculated inside me, now im utterly worried that i could get pregnant from this, what are my chances? Also do you still have 'most fertile days' on the implant?  Im taking a pregnancy test on the 21st or 22nd of March as my period is due on the 19th, and i know the implant can mess periods up too  I know the implanon is supposed to be 99.9% effective, but i've been reading internet horror stories that people have gotten pregnant on it. Can the implanon mess up a pregnancy test? Im scared, please please help me.

Answer
I don't think you need to worry.  Imlanon is more than 99% effective in preventing pregnancy.  This means that for a couple using it for 1 YEAR, the chance of pregnancy is less than 1%.  If inserted just after a period or just after coming off birth control pills, no back up is needed at all.  If inserted at other times, only 1 week backup is recommended.  You should be fully protected after 2 weeks with the implant.  Your chance of being pregnant are far less than 1%.  You don't have most fertile days with Implanon.  It's true that it can change your periods to less frequent, more irregular, etc., so you can expect that.  It will have no effect on a pregnancy test.