Mum moving a month before my exams...?

Well my story is as follows, I am in year 12 in Australia and am a month away from my final exams which are very important to me. Well my mum has met a man this year (around May I think) and she is moving interstate to live with him. She has said she wants me to come too, but ofcourse I will have to stay with my grandparents while she moves and packs (they live near where we currently live). So I have been feeling really unsettled and kinda mad that she has to move right now and cant wait a bit longer so I can have the stability all my friends get while they do exams. Mum has always been like this, we are in our 10th house at the moment and we have lived In Melbourne, The Gold Coast, South Africa some places more than once...and always for the men in her life at the time. Please give me some feedback because I dont want to be one of those brats that seem to try and sabotage their parents relationships by being difficult but I am so annoyed