Invisalign Doesn't Hurt! Does This Mean It's Not Working?

Yes, it is certainly possible to start over with another doctor. There are a lot of variables that can influence the outcome of an Invisalign treatment such as case complexity, doctor experience, and patient compliance.  I would advise you to contact a licensed orthodontist in your area to...

As long as the drink is not colored, sugar free, and cold, you should be fine. Colored drinks, stain them; surgar drinks will get inside and give you cavities in the long term; warm drinks will soften the invisalign, which will not move your teeth in desired position.

The attachments do not always need to be removed for refinement impressions (redo impressions at the end of the first or second set).  If the treating doctor is happy with the make-up of the attachments and their location, she/he may elect to leave them on for the new set....