question: i got the 3 month depo shot for birth control i only got it once 9 months ago since then ihavent gotten it ive been having unprotected sex  i got my period 2 months ago for 6 days and then ididnt get it again i took a pregnancy test 2 wks ago then came out negative itook another one yesterday and came out invalid only one line poped up ive been having pain in my under stomach and back pain is it normal what can i do to get my period regular again