Confused period! Any help?

So, I was supposed to get my period about 4 days ago. During the month of July I only had protective sex. Since my period was late my boyfriend and I took a pregnancy test ( first response 6 days sooner) and it was negative but I still have not gotten my period. I’ve also noticed that the length of my cycle has went from on average from 26-28 days to 30-32 days. Should I take another pregnancy test later in the week to be sure? Or is it normal to miss a period?