If you had intercourse without any form of birth control, your risk for both pregnancy and STDs is high.
What's The Risk? - Five Easy Risk Assessment Flow Charts
A Quickie STD/STI Risk Assessment
As your period differed from what it was usually like, I'd recommend taking a pregnancy test. They give reliable results either on the first day you miss your period, or ten days to two weeks after the unprotected sex.
So take a test now, and if it comes up negative, make sure you test again to confirm the result in a week.
Also, call your nearby sexual health or Planned Parenthood clinic and get yourself an appointment for an STD screen. While you're there, you can also get reliable birth control and grab some free condoms, too.
Hope this helps.
"Through repetition the magic will be forced to rise."