So many questions....... I completely understand, I am exactly the same on an aeroplane! I usually leave a big hand mark on my husbands arm after we've taken off because I hold onto him so tightly!!! In my opinion you have chosen the best airline, Virgin are the only ones I will travel with long haul as they are so kind and helpful, the plane will be a jumbo so you will have much more room than the flight you went on last time. The toilets are not huge but you won't be in there for ages so don't worry about that. I take chewing gum with me and as soon as the plane starts to move i put 2 in my mouth and start chewing, alternatively you could suck on a boiled sweet until the plane has levelled off. If you read, take a book, they do have films you can watch. If you do feel anxious the cabin crew will do the best they can to help you so don't be frightened to ask.
Good Luck, not that you'll need it and enjoy your trip