I’m really sorry to hear that.
So, you did not have Time Machined those pictures right?
Did you log in via Apple ID to see if the pictures were there? Did you use the paid storage from iCloud?
Apple (IMHO) has changed a bit over the years. I remember iPhoto being left in the past glory and being forced to use Photos. I understand they might have reasons to do that but for me, it was a bad thing for (at least) me. Things stopped syncing smoothly like before.
The same for iTunes. I remember how efficiently and effectively it all synced (iPod touch, iPad, iPhone). But some years now, we do not get to see that.
I still mourn the loss of some great games I had purchased back in the early times. After the iTunes version that ditched Apps, we could no longer sync Apps that we kept on our Macs, unless it was an App that was still allowed to be installed (also related to the 32-bit to 64-bit transition).
Another great feature gone: I could purchase and download a movie onto the iPhone and then sync via iTunes so I did not have to download the movie twice. But now, purchased and downloaded movies do not get synced to the Mac.