Are These Signs...??

Well, my bf and I had sex w/o a condom and im pretty sure he came in me. That was a week and 2 days ago. I was sopose to have my period 3 days ago and I am never irregular, I haven't been doing any stressing to be honest and I havent been thinking much bout the fact I could be pregnat even though I am young. But I have been feeling...Not myself! Like I have headaches off and on everyday, I feel sick to my stomache and sometimes have sharp pains througout my belly. I dunno if these are early pergnacy signs or not but I jus do not feel my regular ol cheery self. Could I be pregnat!? And another thing... Is there any way I can find out for sure I am pregant this soon? Please, help in any way if you can. Thank you! means alot!