Pregnant??? HELPPP

So my period is late a little more than a week but my cycle is irregular (usually 5-10 days late)(mylast period was on the 27th of November). I have had sex multiple times this month, most of it unprotected but using the withdrawl method. Last night (when I was late 7 days already) i had sex with a condom but it broke and we didnt realize until my SO had come inside me. I took a plan b about 2 hours later but it says it is 89% effective. Should I be worried?(i am always tired, i have a sharp pain in the lower abdomen(not like pms but pain), i urinate often and i am always hungry). Could I be pregnant??