pregnant or paranoid?!

I had unprotected sex on the first and was supposed to start my period the 4th.. however, I'm irregular and haven't had my period in like 4 months. I keep this app bc I still get period symptoms w.o bleeding /// question is. could I be pregnant? I keep having stomach pains and even though it's only been a lil over the week, should I test or wait awhile? I know you can take a blood test at the dr w.in a week