I have been on the depo shot for over a year and now having some strange symptoms

I need answers!! Hi guys, I’m 16. I have been on the depo shot for over a year now, November will be two years. My period has completely stopped. But I have had spotting once in a blue moon. I have not had sex on the depo shot until October of last year. My boyfriend and I have been having sex for the past 4 months. We use condoms, but sometimes we do not( he does not cum in me).Mid January I started to have light spotting, but was not alarmed because I just thought it was due to the fact that I was due for my next shot in just a few days. Now it is mid February and I have been overly tired, some back pain, just not feeling myself some points through out the day. I have had a thick discharge (with no weird smell) for the past two days, but it has gone away since I had used the baking soda bath solution. I did order pregnancy tests that will be coming in the mail soon so I will update once I take the test, but please let me know if anyone else on drop has had these experiences !!!