How To Reduce Bleeding And Spotting While On Depo Shots?

Hi there, I m 21 years old and am currently on the depo shot, this is my second course of the injection. I had it reinjected on the 19th of September and have been bleeding/spotting new and old blood for the past 3 weeks. I am beginning to wonder if I should change methods of contraception or just give this one some time. i m not due for my next injection until December 20th. I have also had issues with the pill which made me nauseous, and the implanon which also gave me continuous and irregular bleeding for over 2 years - I even tried this in conjunction with the pill. I m wondering if there is anything that can be done to treat or reduce this continuous and inconvenient bleeding/spotting? My obstetrician suggests getting the marina inserted (I have not had children before), however I m starting to get frustrated thinking I will continue to experience this bleeding with this method too. I do not have my appt with her until next week, however my frustrations are getting the best of me and am wanting some answers as to why this is happening, and what happens if this method of contraception doesn t work either… Thanks!