Bridge material question

[davidrk13]

so now that the bridge is completely done i realized some weird things, like that when its perfectly level the weight force it takes to push one side down is waaaay less then the other side so i just screwed some blocks of wood to the harder to push down side bottom to balance out the weight and it worked to fix that problem but its now completely not level when there's nothing on it so im scared that it wont be accurate when it comes to testing did anyone have a similar problem? or know if it will effect the testing?