Etonogestrel
"I have had this in for about 2.5 years. It works in that I have not gotten pregnant.  I have a very light period for 1-2 weeks every month or so.  Sometimes 6 weeks in between 'periods,'  sometimes only 2 weeks. It's very unpredictable, can ruin a lot of 'underclothes'. Also, I cannot get back to my pre-birth control weight. I used to weigh an athletic 145 with a diet of whatever I felt like eating and exercise 4 days a week.  Maybe its age, but now 2.5 years later, I can exercise 6 days a week for  twice as long, and watch what I eat and am stuck at 154."