My Period is 6 to 7 days Late. I did a pregnancy test and it turned out negative.
I have had unprotected sex 6 days before my period was due.
I am used to having irregular periods, but I feel that 7 days is too long.

Most likely your period is just off. While sex several days before a period is due can result in a pregnancy, it is not the norm.

Give it another week and try another test if still no period. If negative, wait until next month and see what happens when your period is due.