Is it possible?

I'm on the depo shot and my mom told me that the doctor said I wasn't supposed to start my period on the shot... At the end of the month I started my period while still on the very first shot... I had sex like 15 days after that and I've been having the same symptoms that a pregnant woman has except I have t had morning sickness and I haven't started yet this month... Any ideas on what this may be??? I'm curious on people thoughts... Especially, for other woman like me that has had the depo shot... 🤷🙏🏼