Hi, Thanks for Healthcaremagic, It is normal not to have period during lactation or when you are feeding your baby. You got your period 5 week ago, and now you have missed your period if you had unprotected sex during this period we need to rule out possible pregnancy. This is good that your urine pregnancy test is negative. You should take another pregnancy test, or you can do Beta HCG to rule out pregnancy. You can consult Gynecologist and go for transvaginal ultrasonography. It is possible to become pregnant while feeding because ovulation can occur in between so it is advisable to use some kind of contraception such as copper T, IUCD or barrier methods like condom. Hope this information helps you. Take care. Good Luck. Dr.A.Dubey M.D.