Your relationship is in a really early stage for her to be talking about marriage and babies in anything but a general, future sense :) I agree with adgal, get and use condoms and have a real heart to heart serious talk with this girl about your relationship.
As far as is she or isn't she. I've never personally gotten a false result from a home pregnancy test. I have seen women who focus on the possibility of being pregnant so strongly that they induce all sorts of symptoms...my son's girlfriend was CONVINCED she was pregnant...she had all the symptoms-morning sickness, no period, sore breasts, growing girth...blood test showed NO hCG...so no pregnancy...but she was SURE until she got the blood test results (and they always used a condom)
Have her visit a doctor...and have a serious talk with her :)
OK i took 5 at home tests and all said negative. When i went to the Dr i was positive that's one thing don't check so close to the missed period and try clear blue have her pee in a cup and dip the stick that's the only at home test i came back positive and im due to have my second child so i do agree be honest if your ready for a baby and to settle down. My first child's father said he did and when i found out i was pregnant he ditched and is stuck paying child support which he's getting in trouble for because he's not paying hope that helps
Well, if she is using the home pregnancy tests according to directions, and they are coming up negative, chances are that she is not pregnant. However, with a missed period she should probably see her Dr. for blood work to be certain. Symptoms don't really mean much of anything as there are other things that can cause the same symptoms such as stress or a host of other things. But still, a trip to the Dr. is warranted.
That being said, if you are not ready to be a dad, I wouldn't rely on the pull out method. Kinda like playing Russian Roulette. It is not effective and whether or not you pee before hand has nothing to do with it. I'm not sure why you think that's important? Sperm isn't found in urine. You need to discuss and use a more effective form of birth control. Double up by using a condom so that you are taking responsibility as well for not putting yourself in that position. You two also need to be honest with each other as to when you want a family.
Good luck to you.