Had unprotected sex for about 10 seconds and he didn't cum inside me. took the morning after pill within 12 hrs i definatly won't get pregnant will i?

Can't say 100%: You can never say 100% but the situation you described it is unlikely that you will get pregnant. Plan B within 48 hrs of intercourse is 94% effective to begin with.

Not Probable: Given the scenario you detail, it is probable that you will not become pregnant. From the phrasing of your question I am reading between the lines you are anxious about this and hoping not to be pregnant. Use protection with condoms every time to lower rboth pregnancy and STD risk.