period help please.

Kayci
hello lovely ladies, I have regular periods and have for the last few years, lately it's been off and odd. 
Back in June I had a very light 10 day period,
July I had no period. 
And now in August it's very light and on the ninth day. 
Just wondering if it is possible that I'm pregnant or if stress can cause your period to act up. it's very odd for me. 
also my period hasn't been irregular in years but when I got with my fiancé about a year ago I missed a period back in March as well but April it was a regular light-heavy period for seven days. 
would love for a little input on this. thank you so much.