Welcome to HCM.
You are on Implanon
for 1 and half yr. It is sub dermal contraceptive
implant and gives protection more than 99.5%.
Your features probably due to hormonal
imbalance and psychological upset or stress
. It is more resembles with Pre Menstrual Syndrome.
If you missed your period,then do a home pregnancy
test after 1 wk to exclude confusion.
So take healthy diet, avoid stress by doing regular deep breathing,do regular exercise,avoid tea/coffee & salty/spicy food in 2nd half of cycle,drink lots of fluid,proper sleep and wear tight breast support to relief symptoms.
Be well and practice safe sex in future as you are too young.