No.
As soon as your first missed period.
If you had unprotected sex then there is a high chance.
probaly
If you are still under 18 years old then your cycle may not be regular yet. There are a few other things that can cause a late or missed period. Stress and diet change can also cause you to have a late or missed period. Any time you are concerned about something that is going on with your body then you should be seen by a doctor or medical practitioner. It can ease your mind if nothing else.
If you had a regular period after unprotected sex, you are not pregnant.If you had sex after that period you may be pregnant.If you are unsure you can use a regular pregnancy test available at any pharmacy, they are very accurate if you missed your period already. If you did not miss your period yet, the pregnancy test is less accurate.
you could be, get a test to be sure
You can take a test anytime 2 weeks after sex.
Since you don't tell us how old you are I am going to assume you are young and just started your periods. If this true a young woman just starting her period will have irregular periods for the first year or two. Also some periods cycles are longer than 28 days and can go 35-38 days. If you have NOT had sex a missed period can happen. If you have been sick a missed period can happen or if you have started a athletic program it can happen. Many things can cause a missed period, but if it continues see a doctor.
No, sex during menstruation does not cause gonorrhea. Gonorrhea is an STD, it would be transmitted via sex.
Have you taken a test yet? You should.
Go to your local health clinic and have them look at you. you might be preggers. Avoid unprotected sex at all costs.
Of course -- the only safe sex is no sex at all. A pregnancy test is usually effective 3-5 days before a missed period. Take one.