To be safe I would go to the doctor to see if you are pregnant, he/she will know for sure. However, you can still bleed while being pregnant, looks like you are pregnant! if you toke the test at the right time, in the right way it is 99% accurate. If you are, listen very carefully, you must smooth things out with this boy, being pregnant is a very serious deal. As much as we like to drive our point home in an argument, it is not always the best thing to do. A good trick to do is humble your self a bit, and become very neutral almost, then he lets his guard down and suddenly feels more understanding. ( it works like a charm! never blame or accuse) As well some of the arguementing might of resulted from the stress of your lack of period and possible pregnancy, I know that when I thought i was pregnant, and was stressed all I did was cry on the phone to my boyfriend everyday. Take drastic action. Calm things down for your self as well as with him. Then after awhile talk to him about your current situation of being "pregnant". What are you going to do, If you honestly deep down think that things won't work out then it's all up to you, but if you think that maybe things just got a little rough due to outside factors, keep him, and deal with it together.
God bless you!! Mel