extremely late period. help!!!



So the last time i got my period was on the 16th of september. However, October passed and i didn’t get my period. Today marks officially that my period has been absent for 2 months. I took 3 pregnancy tests and they all came out as negative. I don’t have any symptoms and i’m 18.

I travelled from my home country to france on August 28th.

So is there any reason on why i missed my period?