I had unprotected sex a day before ovulation. took plan b 23 hours afterwards. i am overweight, could that have effected the pills ability to work ?

Perhaps: There is some evidence that emergency contraception (EC) progestin-only pills are less effective if your BMI is >30. Ella/ulipristal acetate may be more effective than the Plan B/progestin only. Having a copper IUD inserted as EC is the most effective, 99%, equally so among all women regardless of weight. Reliable non-emergency contraception is your goal. Best wishes:)