Lex, maybe your hymen was torn a little more during your sex. That would explain the blood. If he did make a deposit inside you need to know if you were in your "fertile window", cycle days 8 thru 16 of 28. Any other time the chances of pregnancy are pretty low.
Download a period tracker app so you get an idea of the most fertile days, reseaarch "signs of ovulation" to correlate with the app, buy some of your own condoms and vaginal spermicide, use consistently per instructions and recover costs per entry!