Depo Shot vs Pregnancy

Patient: I had the depo shot after my period. I had sex a few days after. I had light bleeding for a few days, about a week later. That was about three weeks ago and I havent bled since, but Im having a lot of symptoms. Since pregnancy symptoms and depo shot side effects are so close,what do you think?

Symptoms: Nausea, change in appetite, etc..

Doctor: