PREGNANCY TEST QUESTION? - Please read i REALLY need answeres??

So here the story goes: I have been getting all the signs & symptoms that i am pregnant ive been getting them for about 2 & a half weeks now ... i have takin about 3 pregnancy tests all cam up ''Negative'' 1 line! & i took another one today when i first woke up to go the toilet in the morning & i held the pregnancy test stick in my urine stream for about 7-8seconds & it came up with 1 dark line & then i left it on my dressing table in my room & went back to it 10mins later & they their was a very VERY faint line? Now ... The faint line was a really think line alot thinner to the thick negative one so i waited about half an hour & then i took another test & then it had no faint line at all? only 1 negative line WHY? what does that meen? but when done the first test a bit of my urine when on the actuall window of where the lines come up? & thats why im thinking thats what made the other 2nd fainty line come up cause i accidently pee's on it & i think my urine got inside of the window?