Could implantation bleeding occur two days after unprotected sex even if he pulled out?

Possible: Even a small amount of semen or "pre-cum", has manysperm which can lead to pregnancy. You need reliable birth control. I urge you to see your gyn to discuss this. You are a bit too early to detect the hormones in a urine pregnancy test. Would be able to check in about 2 weeks.

Not that soon.: The pull out method is very unsatisfactory for prevention of pregnancy. When implantation bleeding does occur (most often doesn't) it just causing a drop or a couple drops of blood.