Ok, soooo... I figured it out. Sort of.
When I log onto my Google account online on my laptop, and I go to my contacts, I noticed that when I search for a contact that is missing on my phone, I could pull it up online. However, if I just scrolled down to find them instead of using the "Search" feature, then I realized that they were missing from my online Google account as well. In other words, the missing contacts weren't listed in my "Contacts", but if I "searched" for them, they could be pulled up.
Then I noticed that if I went to the pull down menu, there at the bottom was the option to "go to the old version." When I did this, the menu changed from just "Contacts" to now showing two sets of contacts. One listed as "My Contacts" and the other listed as "Other Contacts." All my missing contacts were under "Other Contacts." I was able to select them all and "Add to my contacts" which added them back to my main list and then populated them back on my phone.
I have no idea how this happened to begin with, so I don't know if this fix will last, or if I will have a recurrence in the future.