PrupleBlue

I don't think the OP was stating anything was lost.
If you file for AOS after 1 year from the medical, then you need to do it again. If his vaccination portion was marked incomplete, then he needs to only fulfill the vaccination requirement.
Medical Examination of Aliens Seeking Adjustment of Status. If you are a K-1, K-2, K-3 or K-4 visa holder the I-693 instructions state that you are not required to have another medical examination as long as your Form I-485 is filed within one year of your overseas medical examination. If you are missing any shots from your overseas medical a I-693 vaccination transcription is required to be completed by seeing a Civil Surgeon to have certain portions of the I-693 completed and have the Civil Surgeon certify the form (sealing the original in an envelope and giving you a copy).
If the medical is within one year AND the vaccination requirement was fulfilled at the time the medical was done, then nothing needs to be done, it will already be in the sealed packet you he handed over at his POE.
See instruction 11 from the VJ AOS Guide for K1 here (actually use this guide as a checklist for your packet)
Yes, only send in a photocopy of the I-94
Yes you need to send a copy of your marriage certificate. If you have other evidence, then send it in. USCIS understand that K1 couples who adjusting status have just been married. This is one of the reasons for the 2 year conditional green card.
Good luck and hope this helps

I REALLY REALLY REALLY advise against cancelling the K1 and trying for a CR1 - (don't get married either cuz that could screw things up for you too since the purpose of the K1 is so you CAN get married) - from everything I've read on this site you would be in for another year or two of waiting (seems like the visa process is taking longer and longer due to backlogs) and it does not sound like you are eligible to expedite...you would most likely get AP again too since you never gave your first AP a chance to finish... It's kind of like waiting in a super long line at the grocery store, getting fed up, and going to wait in another super long line that takes even longer... I know it's hard but just try to be patient...Bangladesh seems to get out of AP quicker than others like Pakistan...does your fiance have a really common name? That could be the hold-up - I'm pretty sure that's why we have been waiting for so long... I know that it stinks...but try to wait it out - you already know how hard this process is and you don't want to do anything to compromise it....