Got into some trouble, really need ur help!!?

im 16 n i got into trouble with some friends, they caught us around n area were they found a pipe, n know we have like a miner probation. Anyway i can tell n my dads face that he is like ashamed of me!! i hate this feeling, i kno i scewed up but i want my dad still b hiimself around me. I have a pist test tomorrow, n i have never smoked weed b4 n my life, so im sure the test will come out clean, but my dad n my probation officer thinks that im lieing to them!! N today i asked my mom wat she wanted for mothers day, n all she said was for me to come out clean. i nvr smoked but im the kinda person that i will always doubt myself no matter wat so im scared it wont come out clean, but it has to right cuz i never smoked weed n my life!! plz help me how do start getting things to get back to normal?? i kno its gonna b hard but i jst wanna make things a lil better. Any suggestions??