What Causes Abnormal Menstrual Discharge Post Contraceptive Implant?

Hello. I had a contraceptive implant put in on the 14th of January and started bleeding on the 28th of January which I knew was normal but I have been bleeding ever since (which is until 22nd February) with only a break of 2 days which was on the 7th and 8th of February. On the 19th of February I was given contraceptive pills by the sexual health centre that I go to in order to stop the bleeding. I asked the lady who have me the pills when my bleeding will stop and she told me that it totally depends on my body which I understand but she did not tell me how long it can take to stop the bleeding by taking these pills. I would just like to know how long it may take approximately. It would be great if you can help me to get the answer for my question. Thank you.