What would cause my period to be like this.?

I'm 21, my period is regular. I have bad cramps the first day, and then I'm fine. I've had my period since I was 12.
I'm 5 feet tall and 113 lbs.
Up until about 8 months ago, my period would be 5-7 days.
For the last 8 months it usually only lasts 2-3 days. It's regular the first day with bad cramps but by the second day I technically wouldn't even need a tampon because it's so light.
I am in good health as far as I know, not pregnant of course and no stds.
The only thing that's changed is I have gone from 128lbs to 113 lbs since January.
Is this normal? What would cause this?

julia2015-07-06T21:11:20Z

It's normal for your body to change as you get older (I went through something similar at 23), but your weight change may definitely be a contributing factor, especially if your weight was extremely consistent before the loss. Was the loss due to you starting a new exercise regimen? That may also be the culprit as exercising more releases endorphins into your body which can effect your hormones (everything in your body is connected!). As long as your period is somewhat consistent and not suddenly painful (not regular cramps) or irregularly colored or lasts a really long time, I would not worry!