I just started a second round of Invisalign (the first round didn't quite get all of the tooth movements that were projected). My ortho indicated I could change trays weekly using an accelerating device (Propel VPro5). The first set of trays fit fine, and I have just moved on to my second set of trays. The bottom tray fits over my teeth well. The top one fits over my teeth, but is loose over my back molars (no attachments on these teeth, when I bite I feel the tray push up). Otherwise, the tray lines up with attachments etc. I feel some soreness around front teeth, so clearly pressure is being applied in that region. There is some space in the trays for front teeth, but it seems like the normal amount you'd expect at the start of a tray. Is this... OK? In the past, I knew I wasn't ready for a new tray when it was too tight for my teeth. The issue of a tray being loose is new to me. I'm so tired of Invisalign, sometimes I think regular braces would have been better. Your insights are welcome!