hi there,first of all stop worrying and go about methodically about the whole thing. You got your period even though it is a day late, which is not abnormal but sometimes does happen. Still to put your fears at rest get a home pregnancy
card and check your urine. The breast tenderness is only on one side which suggests that probabely you have hurt it during foreplay. Put hot fomentation and take an anti- inflammatory and if it does not feel better in a day or two then you need to show it to a doctor.Your pains and sick feeling will disappear in a few days if you relax and don't worry so much about it. If your preg card test is positive then you do need to inform your elders and let them take the necessary action. Till then relax ,I am sure everything will be fine Take care.