Hi Jojeepoj
I really hope that the trip goes well and that you don't experience too much turbulence. I know it can be unsettling but it really is nothing to worry about, but i know that doesn't help! I flew back from Florida recently on an overnight over the atlantic, and the seatbelt sign didn't come on once, it was a very smooth flight, at times it was easy to forget we were on a plane! Equally I have had some bumpy flights over the atlantic at night where the seat belt sign has been on sporadically, so it is difficult to know for sure what you will experience. It might be worth letting the cabin crew know that you are a nervous flyer so that they can keep that in mind and check on you if needs be. Just try to relax and remember that it cannot cause you any harm.
I wish you all the best for your journey
Lorelai