Im 20 yrs old. my boyfriend and i have unprotected sex. Every month when my period comes i usually go for a full 7 days. I always know when its coming i can usually feel the cramps a week before. This month when it got here i didnt have any cramps or anything like that until the day when i started they lasted about a day. And 2 days later my period was over. This isnt normal for me since i first started my period when i was 13 i always go 7 days exactly. Is something wrong or is my body just changing?

Since you are still having a period, I wouldn't worry about it. It sounds like your cycle is just changing or could be effected by stress. Your cycle will most likely not remain the same your whole life. It's normal for women to have 2 and 3 day cycles.

You said you always have regular cycles up until this one time and you have been having unprotected sex. You stated you had a period that lasted 2 days, have you given any thought to the idea that maybe you could be pregnant? I have known a couple of women that have had small, short cyles like this and were pregnant. I would take a pregnancy test and in the future I would refrain from having unprotected sex unless you want to have a baby.