Trying to get pregnant but suddenly getting periods late by 10days

Hi Everyone,

Need some advise here. I used to get my periods exactly in 30 days, but since last 2 months my periods are getting delayed, last month it got delayed by 4 days and this month by 10days. I am trying to get pregnant and this delay is driving me crazy. I have been trying to concieve since the last 4months. I took a home pregnancy test 2 days ago which came out negative. Can someone please help me here. I am very worried and dont know what to do.