Hello and thanks for your query. I shall make an effort to provide you with good professional recommendations specific to your questions. A drop of pre ejaculate is enough to cause pregnancy. I think based on the information provided, you are less likely to become pregnant. But if you miss your periods i advice you to test urine pregnancy test. Most experts advise that you should wait at least one day after your missed period before taking a home pregnancy test, though waiting a week is considered best. This can be tough when you are anxious to find out if you re pregnant, but waiting allows for a higher degree of accuracy when taking the test, as hCG levels rise rapidly in pregnant women. It s best to do the home pregnancy test first thing in the morning, when your urine is most concentrated and hCG levels are highest. So I advice you to perform a test a week after missed period and with morning sample of urine. This test kits are nearly 98% accurate, so reliable. With transvaginal ultrasonography, the diagnosis of pregnancy can be made earlier by 4-5 weeks gestation I advice you to use some method of contraception when you are not trying to be pregnant. Yet again, I duly appreciate your query to me, I do hope that you have found something useful to help you and I shall be glad to answer any further apprehensions. Sincerely,