pregnancy test doubt

i peed on it for like 5 seconds but the result came negative pretty fast and it stayed that way after the minutes i was supposed to wait, which apparently is a good thing bc its not supposed to change if the result is accurate, also it had an "invalid" display, my doubt is if i hadnt peed enough it would came out invalid right? this was like more than two weeks ago tho and i had sex last month and havent had since then so i probably would know by now