Question roughly speaking girls and pregnancy?

My girlfriend just switch from birth control contained by the form of a pill to birth control in the for of a shot (apparently like thing) and she got her interval last sunday and today is sunday. Her length stopped the day past yesterday and didnt bleed yesterday either. But today she bled for for a time bit and stopped. Is that normal somehow or is she pregnant or something? its commonplace if she is on the shot. its just the hormone side effects.
she's lucky. when i be on the shot, i bled for the whole time the shot be in my system...3 months!...never ever again!
She have been injected next to Depo Vera and this is very common... no she isnt pregnant.