Photos gone missing

[RustBuckle]

I decided to update my old 4th gen iPad that was running iOS 7 to 10.3.3. I first backed up the iPad on my iMac (first time connecting it to my iMac in over a year) through iTunes. Then, I went into my photo app on my iMac and copied the photos from my iPad over to my mac. Then, after updating the iPad via iTunes, my photos library on my mac is now only showing old photos from my photo stream and iPad, and is missing the photos synced to it over the past year or so from my iPhone. I don't pay for extra iCloud storage so most of my current photos aren't on there as I maxed out my allotted storage space some time ago. Where did all my other photos go? Help!