Can someone help me out a bit?

okay so I am sexually active and on birth control and use a condom always. so my time of the month rolls around and the days are either Tuesday or Wednesday and so as Wednesday comes I feel the bad cramps and I am waiting for it start..I decided to take a test because I didn't get the normal brown discharge like always and as I take the test and am wait for it to fully finished I wipe and start bleeding. the test was a soild negative. so I go on with my normal life. two days of normal period then one morning it is very light and stops for a whole day. still cramping and then on Saturday (last night) it lightly starts and then once I put a tampon in for an hour and then take it out, it is straight brown. mind you I am still cramping. since then I have been fine. normal period is 3-5 days. I will retest. but kinda freaked. thanks!

* I usually always have a day where my period stops but I am still freaked