I'm 15. Could I Be Pregnant ?

i know i must be just overreacting but i'm really paranoid. me and my boyfriend of 6 months had on the 19th. we used a condom and he started to *** inside me but then pulled out and finished with the condom still on. i saw the sperm in it myself. and it definetly didnt break. my period comes on the 23th. most of the times its earlier but never this late . i'm still planning on waiting a week or 2 before taking any actions but i'm still scared shitless. its the 25th and i'm scared. i keep getting lower stomach pains too. what does this mean? am i overreacting? what should i do?