My first day of LMP is on 24/07/2014. I had sex for a week starting 16/08/2014. Am pregnant now. When did I conceive an when is my due date?

Plugging those numbers into the calculator at BabyCenter | Advice and support on pregnancy and parenting I get:Monday, April 13, 2015.

Your conception day lies on one of the days you had sex in August after your last period. It is impossible to narrow it down further due to irregularities in when you could ovulate and how long sperm can last in your reproductive tract.

You're about 28ish weeks along, have you seen any sort of doctor about this pregnancy? If not, now is a good time to go.

There's really no way to track down the exact day you conceived.

Your OBGYN should have told you your due date. Are you not seeing a doctor? Are you at least taking prenatal vitamins? It's very important to have medical help during pregnancy. You should be seeing your OBGYN at least once a month until your 8th month, and then every week for the last month.

Is this a question of paternity, is that why you want to know when you conceived? Are there two possible fathers?