Originally Posted by
Alty
Yes, a missed period is a sign of pregnancy.
There is no form of protection that's 100%, so anytime you have sex, even with protection, pregnancy is possible.
False negatives are very common, and at this early stage, if you are pregnant, it would be too early to test. Wait until your period is at least 2 weeks late, then test using first morning urine. If that test is negative wait for your next period, and if you miss it test again or get a blood test done.
Pregnancy is possible any time you have sex, so if you're not ready for a child, you should abstain from sex, that's the only method that's 100% reliable.