I am 26 years old and I have always had a heavy 6 day period since I was 12. Last month when I had my period however it was barely there, really light/watery and lasted about a day and it appears the same thing is happening this month. I know for a fact I am not pregnant because I am not currently being sexually active and haven't been in months. I did start being more physically active recently however and I heard this can have some effect as can stress but, I wasn't really stressed about it until the light period happened again.