I'd like to do a course Invisalign but I'd like to know how it feels before signing up for it. Does it feel different to whitening trays? I recently whitened my teeth and I struggled wearing the trays all night for 2 weeks. They felt very thick and rigid. Does Invisilign feel the same? I've always had quite chubby cheeks, and I still have the scars from where my old retainer used to rub as a teenager. Do the trays cause irritation?