Preganancy related issue. Be pregnant?

Hey my friend is 17 years old and she had unprotected anal just 1 day after her period ended. She had her periods that months which was just 1 day late and was completely normal, she had no symptoms of pregnancy but constipation. But she was still worried that she could be pregnant so she took the pregnancy test on the day when her period was supposed to come, it came negative and she started off with her period just one day later. Now, she is supposed to have her period this month but she is two days late also she had sore throat with white patches and cold and was on medication for 7 days but she is worried that she might be pregnant. She is still not having any symptom of pregnancy no nausea vomitting morning sickness frequent urination low back pain nothing but she is just too worried. Could she be pregnant?