Essix Retainer Question

I am a dental hygiene student and I recently had sealants put on my teeth. After receiving the sealants, my original essix retainer no longer fit; some of the sealants must have been overfilled. Since all of my teeth do not properly occlude, the sealants did not show wear on the articulating paper and were not taken down with a burr. My orthodontist cut my retainer from canine to canine for me to wear. I requested that they make a new full retainer because I wanted all of my teeth to be retained. If I wore the cut essix canine-to-canine retainer, would my premolars and molars eventually move? During the impression for my new essix retainer, my maxillary and mandibular anterior teeth hit the front of the metal tray (It felt like they hit on the facial and insical edge). The dental assistant said that she could fix it on the model. She said if it won’t work they might have to get another impression later. I have paid for the retainer but I have not picked the retainer up yet. However, I am concerned that the retainer is not going to be correct since the impression was not done 100% correctly. It seems like there would be some guesswork involved while fixing/sculpting the model. I have been out of ortho for 7 years and I wear my retainer every night. I do not want my teeth to move. What are your thoughts on this? Thank you for taking the time to answer my question.