pregnancy rate of women while using Implanon?

Hi,
Welcome to ehealthforum,
The failure rates for Implanon use has been said to be about 0.38%. Your symptoms do suggest possibility of pregnancy. If you suspect to be pregnant, you should visiting your doctor/gynecologist at the earliest for further examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). If pregnancy gets confirmed, Implanon should be removed immediately. If pregnancy gets ruled out, further investigations would be started to look for any other underlying cause for your changed periods. Treatment as appropriate would be started based on examination and investigation results to help you regulate your periods. Although sometimes, you can experience lighter periods while being on the hormonal contraceptives, (and the weight gain, mood swings, tiredness could be attributed to hormonal content of it), it is better that you get a thorough evaluation/check done by your doctor/gynecologist.
Take care.