Contraceptive implants are successful and reliable method of contraction. Milk production is dependent upon a hormone called prolactin. During pregnancy this hormone is present in high quantities and may lead for milk production in some ladies. But prolactin levels can also be high in non pregnant ladies causing milk production. Although chances of pregnancy are poor in your case So, you should get pregnancy test and if the test is negative then take prolactin inhibitors. Your doctor can guide you in better way.