wearing retainers and bite guards?

First off, I have had braces, and now am wearing retainers. I got my braces and retainers from my orthodontist, and I saw my family doctor and dentist about clicking sounds when I open my mouth, my doctor said it could be TMJ. My dentist talked about what was happening to my jaw, but never actually mentioned the word TMJ. He made impressions for my teeth to make a bite guard. He told me I would only wear retainers on my bottom teeth, and at the top, I would wear the bite guard. He also said the bite guard would replace my top retainer. The bite guard is a regular bite guard, but I did some research on the internet and found that people who need retainers as well as bite guards get a Retention Splint, which serves a dual purpose as retainers, and bite guards. My dentist said that the wearing one retainer and one bite guard may not fit properly. I don't want to have to pay for it if it doesn't work properly or if it will cause my teeth to go crooked again. What is worrying is that the impressions were not made well (in my opinion). As I had impressions made when I had retainers made from my orthodontist. My dentist was constantly moving the mold around, and finally left the office for a few minutes while he left the mold in my mouth without anyone holding it in place. He seemed very worried while he did my impressions. I have not yet picked up the bite guards. My orthodontist cannot be reached, he only has one receptionist on duty and the rest are ill, as a result,  phone calls went to the voice mail. I am a university student, so I do have a bit of knowledge in biology. Am i over worrying about the impressions my dentist made, or are you supposed to jiggle the mold (this didn't happen at the orthodontist)? Will the bite guard actually work as well as my retainers?