Whats going on with my period...?

Im in my 20's and my period seems to be very light...One month I will get my period on the 20th then the next month it will come on the 27th...Why is my period like this? Its been like this since I started when I was 14 years old. Im currently on my period now and Its been 3 days and seems like nothing is really there. I have lost 5 pounds, Ive been somewhat stressed out. I know this may have something to do with it but Its really been like this for YEARS. Will my cycles ever get "heavy" or in other words "normal"?