My last period started on the 4 and stopped after 4days. i had unprotected sex yesterday with my husband and is like he came in me. i just took posti?

See below: Plan B is about 95% effective if taken within 72 hours of sex. Conception, as defined by the generation of a fertilized ovum, occurs within day or so of the sex. However, it takes about 3 weeks for the embryo to make enough HCG to produce a positive pregnancy test. Blood test may be done a day after a missed period. Home pregnancy tests should be done 4-5 days after the missed period. If the result is negative repeat the test in 4-5 days. Use first morning urine and follow instructions for the test carefully. If you do not wish to be pregnant, use contraception all the time, every time. You may consider implanted contraceptive, or IUD. Practice safe sex