After sex, notice sperm seems leaked at the bottom(root of my penis).does it mean it leaked?and thus likely to get pregnant?

Ye, it can: Yes, your partner can get pregnant if you leaked sperm. If your partner is not using a reliable form of contraception like the pill, iud, patch or ring then you should use a condom. If the incident occurred with the past 3 days, she should take plan b. If it is in the within 5 days then Ella (ulipristal acetate) the new emergency contraception should be used.