I haven't been wearing my invisalign "braces". what could happen?

Teeth can shift: Your teeth can shift, aligners won't fit correctly, new impressions will need to be taken, treatment will be prolonged, and orthodontist may charge an additional fee for time and materials since you were not compliant.

Besides wasting your: Money... Teeth will not be aligned as planned, re treatment might be necessary at additional cost, will take longer to treat. Really nothing good. Hope this helps.

Relapse : Your treatment can relapse , when the teeth were not moved as planed, you might need re treatment at additional cost

Shifting: your teeth will begin shifting back to their original positions-- as same given what I am sure you invested in invisalign! I would see your orthodontist immediately and, if you have the old trays, maybe they can recommend a way to get back to where you were with the old trays

Waste: Waste of time, effort, and money. Medicine doesn't work if you don't take it. Clear aligners don't work if you don't wear them. Call your treating Dentist or Orthodontist ASAP.