Late period, am I pregnant or whats going on

My period was supposed to come Wednesday and end Saturday nothing at all for 4 days Im 4 days late almost 5 lower back pain and midish uper back pain here and there nausea here and there threw out the day. The night of Day 4 being late (when period would of ended) i have a brown discharge then turns to red/pink VERY watery to where its crazy i never had anything like this before im sorry for the tmi i just dont know what to do had unproductive sex alot with husband trying but not trying kinda just letting it happen and hoping to get blessed with a baby am I possibly pregnant or is this a late period? Im never late. Any answer will help my hopes r up but im trying not to keep them up because i dont want it to be too good to be true. Again sorry for tmi hope somone can relate to what im going threw right now!