Actually I M Getting Worried Cause I Have Doubts Regarding

Actually i m getting worried cause i have doubts regarding pregnancy.me and my boyfriend were doing sex with precaution and i had my underwear but i am unsure about that the sperm may go inside me..actually this happend before 4months..in 20 may and that was also the 5th day of my period.after that i am having my regular period for june july and aug month..and this month my date is on 24th sept..but now i am feeling weak and vomiting so i doubt as i may pregnant so plz reply me soon..plzzz