iCloud photos

hi! So I always backup my phone and I recently had problems with my old phone and I backed it up completely and iCloud photos were on and everything was good, and then I exchanged that phone for a new one. I opened it and clicked on the most recent backup, and a lot of my photos were missing. Random ones too, not just from a specific date, but a whole chunk from each month. I went to iCloud.com and couldn’t find them there either. These are photos I would never delete, and I’m so worried because I need them! Is there a way to find them? Could they be hiding somewhere? The funny thing is some of the photos that are missing, transferred to a new phone during a previous backup, which tells me that they were backed up and on iCloud at one point, but where are they now?