why don't you get a test kit?
withdrawal is not safe but chances of pregnant very very low.
Try not to make her worry, you must be "steady" if she is worry
period will delay than you two will feel worst.
Since sooner or later you will know the result, just get a test
kit.
if + go find a doctor get a date
if - than be careful next time.
sorry, if you don't understand what I am talking about, many guys
here say my english no good, I just want to help.