Why have I missed 2 periods?

My last period was on August 23rd but i've been under a lot of stress. My next one was due October 1st but in September my uncle had a heart attack and was in a coma and died and his funeral was on the 1st so that was a very stressful time and since then i've been under a lot of stress with family and my boyfriend and I was wondering if that's why i've missed my periods?