I had sex on 28th i saw light spotting and peed blood i thought its begining of periods but that was it. could i be pregnant?

Vaginal intercourse with a woman of child bearing age results in a chance of pregnancy. The odds of becoming pregnant are significantly reduced using contraceptives (birth control pills, condoms, etc.), but the only method of contraception that is 100% effective is abstinence. Any woman that believes she may be pregnant should get a pregnancy test and visit an OB/GYN.