Spotting and pregnancy symptoms, am i?

Okay, so me and my boyfriend had unprotected sex on June 28, 2008. When he came, i think he came a little bit in me, but the rest outside my vigina. Around June 8, 2008 my stomache was hurting and i told him, and he asked me when i was supppose to get my period and i told him on around the 26 and i asked why? and he said just wondering, before i talked to him i was kind of worried, so i asked him if he cummed in me, and he said - he thinks? so, we just waited until around the 20's. and on the 21'st i got my period "supposly" usally i have my period for about 5 days and i bleed heavy, but this time i only had it for 3 days, and there was blood the first day but by the 2nd it was turning into a pinkish and brownish. I just thought it was my period so i didnt think nothing of it. On August 3rd of 2008, my head hurted, mah stomache hurted, and i felt liike puking, so i searched if it was possible to be pregnant and have gotten your period and it said no, but there could be spotting. So now im clueless of the fact wheather i am or not. I took a home test, but it was one of the cheapest and it said no, does it matter that it wasnt' so expensive. i also read that sometimes it comes out negitive. But im thinking that i am, i mean i dont know whats it like to be pregnant, but i've never felt like this before either. i lost weight, so its hard for me to tell wheather my stomache has grownn or what. im 14 years old and im scared