I received my first shot of depoprover on the first day of my period. one week later i had unprotected sex. is there a chance i could be pregnant ?

Yes, but low chance: You can get pregnant anytime during your cycle, albeit less of a chance around the time of your menstrual flow. The chance is much higher during time of ovulation--mid cycle for most folks, but it can happen at any time. Ocps, iuds, implants, and injectibles/depo are highly effective, but not 100%. You can check a hpt to see. Consult doc for problems. Good luck.