Perhaps a discussion they should have had with you before fitting the implant!
The implant will have an effect on your bleeding, but exactly what is impossible to say because it varies from woman to woman. It can also vary over time, especially if you haven't been using another hormonal contraceptive.
So.. you could have extended light bleeding but then only only bleed occasionally, or just get some spotting, or...
Did you get heavy bleeding while on the pill?