how soon can you show signs of pregnancy?

I am a family planning doctor from England - so hope my advice helps.

You could be showing signs of pregnancy here, some women do experience symptoms within just a few days of conception.
All symptoms you have mentioned can be linked to pregnancy - but do you have swollen or tender breasts? Light bleeding or spotting? Feeling faint or dizzy? Are you constipated? Do you feel emotional?

If you are experiencing most of these symptoms you could very well be pregnant.

If your menstrual cycle is regular, say every 28 days, ovulation (releasing of the egg from the ovary) normally occurs around 14 days prior to the next period, I.e. around day 14.

Day one is counted as the first day of bleeding and your most fertile time would therefore be from days 10-16.

I advise you take a pregnancy test which you can buy from the store. Look for one that can be taken on the 1st day of your missed period or before. They usually state that you can be tested at any time of the day - I always advise to test the first wee of the day. As the hormone that is released into the Urine that will be detected by the test is at its strongest. However if you can’t wait until the morning - make sure you don’t go to the toilet at least 4 hours before testing your urine as you need to allow as much time for the hormone to be released into your urine.

Hope this helps