Hi Anonymous and thanks for your question.
I'm going to assume you meant to write "unprotected" sex and not "protected" sex. Any time you have unprotected sex, you risk pregnancy. There is no perfectly safe time, although couples who very carefully track the woman’s menstrual cycle and are very knowledgeable about her reproductive system often can, with a strong degree of certainty, avoid pregnancy. But this is not a fail-safe method.
The highest risk of pregnancy is during the second and third weeks of the menstrual cycle. While a normal cycle is considered anywhere between 21 and 35 days, the average is about 28 days. Ovulation (the time when a woman is fertile) occurs mid month, this averages to day 14 every month give or take several days before and after. If a woman has unprotected sex around this time, she may get pregnant. A woman who has unprotected sex has about a 20% chance of pregnancy every month.
To avoid pregnancy, avoid having unprotected sex between days 10 and 18 of your cycle. But remember each woman is different and pregnancy can happen anytime of the month even right after your period, since sperm can stay alive for up to five days.There is especially true for those women with irregular cycles.
The best way to know if you are pregnant is to take a pregnancy test. Nobody can tell you over the Internet if you are pregnant or not. The above information should give you a pretty solid guide as to your risk. Again, your own situation will vary and we cannot give you a definitive answer. A pregnancy test can be taken 14-21 days after unprotected sex and, when taken correctly, should be accurate.
Hope this information helps you.