Yes
no, if you havent had sex.
YOU MAY BE PREGNANT...GET TESTED FIRST...THEN U MAY HAVE IRREGULAR PERIODS IF NOT...THESE ARE COMMON AS WELL
50/100 or 40/100
At 18 you must know how babies are made. If you have had unprotected sex, of course there's a risk for pregnancy. Take a test.
Chances are Good. In fact you may already be pregnant, which is why you aren't having a period.
Not very likely but definitely possible. Take a test just to be sure
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no
yes...pre ejaculation. It doesnt matter if he pulled out.
Unless you have been eating more, exercised less or the period is late you can be as long as you've had unprotected sex. The easy way to find out is buying a test at the store.
there is always the possibility of a pregnancy if you are engaging in sexual intercourse. Check with your doctor, or take an at home pregnancy test
In theory, you can't since you got your period which means that the zygote did not settle or the ovule was never fecundate. However, this is kinda weird since there is, for all women (and girls) exactly 14 days between the release of the ovule and the start of the period.