So I went to my dentist and picked up trays 2, 3, 4 and 5 yesterday. I got attachments put on (6 on top, 8 on bottom) and a bit of IPR around the front teeth. As soon as I put tray 2 on the back left felt a little loose. It fits over the teeth, it's not like its hanging off, but when I bits down at the back I can feel it move up a little, same on the right side but not as much. I asked my ortho about this as soon as I put it in and he said my teeth will move into the gaps if they feel loose, but so far no movement. The front teeth are tight and a bit sore so it is obviously moving those, maybe my back back back ones aren't meant to move? Has as anybody else had this with any trays??i have added a photo of my tray 2 with attachments too for anyone who is interested.