i have a lot of questions

okay i have a lot of questions about the shot. so i got on the shot January 27, i already had my period on January 14-21 , do i suppose to get another period ? another question is does the side affects suppose to hit the same day ? because I started eating hours after I got it and i really don't eat a lot . I've been having mood swings and a lot is making me cry and I'm not really an emotional person . i got on the shot because I have sex a lot . and I just don't want kids right now while I'm trying to get through college and start my career . I've seen where it says hair loss , well I have a sew in in my hair right now and I'm going natural so should i just go ahead and cut my hair ? that's most of my questions for now . if you can help me with any advice please do .