Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern..
Yes
pregnancy is possible despite being on birth control. However chances are very less(less than 1 %). There is no method of
contraception which is 100% effective.
As per your 2nd query, An
implanon birth control cannot cause positive pregnancy test. Pregnancy test detects
HCG hormone in blood or urine, which is different from hormone released by implanton birth control.
Positive pregnancy test means you should be pregnant. However the line should be dark as the other line. As you had a faint line on pregnancy test. You should re do a pregnancy test, this time do it with first urine sample of morning. Alternatively you could do a blood pregnancy test.
Refer to a gynaecologist,As implanton birth control should be removed, if you are pregnant
Hope this information helps
Good luck