If you don't know if you did, I'm pretty sure it's safe to say that you didn't.
you should just get a comfy pillow prob just like masturbating, i might sugest a blow up doll
You can't....
Yes. Sexual Intercourse (sex) is when the males penis enters a woman's vagina so there should be no reason you would not know that you are having intercourse.
ask the person. if that helps any.