What Causes Light Period And Spotting Instead Of Normal Period?

I have irregular period. my cycle is around 40-41days. when i have my period it usually last 5 days and heavy 2 -4th day. my husband and i have been trying to get pregnant. I got my period 2 days ago. the 1st day it seemed like i was spotting. When i wiped it was just light pink. the 2nd day the flow a bit more, very little got on my pad and was similar but the blood was a brighter red. Today in the morning i thought it just just becuase i was going to start my period and my flow seemed to be like when i usually start my period. I just went to the bathroom and it still a bit red to pinkish but the flow slowed down.I took a pregnancy test and it came out negaitive. Is this a sign of pregnancy???