Okay guys, I've returned to this topic because I'm still anxious about this symptom.

For instance, yesterday I was looking at some old photos of my family on vacation. Looking at my mother's face, I started feeling very strange. As if there was something off about her. I mean, of course there was something "off", the picture was taken many years ago and she has changed a lot in the meantime!
Nevertheless, this feeling scared me. I started having concerns about possibly developing dementia and thought that maybe one day I won't be able to recognize my family anymore. Another concern was that I could get psychotic and harm them, thinking they are strangers (by the way, I have OCD and I do often get intrusive thoughts of that sort).
As for the Capgras delusion mentioned before... No, that's not it. I don't actually believe that these people are strangers. I know they're my family, they just feel strange. It's like the classic symptom of depersonalization when you look at the mirror and you feel like you don't recognize yourself, even though in theory you know who you are and that that you do look like that.

But then I also noticed I sometimes have another strange feeling, which can actually be described as the exact opposite of this "people seem strange"-feeling. I can look at someone (usually someone close to me, or a collegue from work) and get this bizarre feeling that they look very familiar, like they are somehow very "real", like I'm hyperaware of them. It even feels like I'm on the verge of suddenly remembering something or making an association while looking at them. Or that they strongly remind me of someone else. Of course, I never remember anything, it's just a weird momentary feeling. It goes away quite soon if I stop focusing on this feeling and direct my attention elsewhere.
And it can actually happen with inanimate objects as well, although very rarely - I will look at an object and feel as if this object is very significant, as if I'm about to remember something if I continue looking at it, but I never do. Although one time I looked at a tile of a fireplace and suddenly made an association with the cover of an air vent in my old house. Why? Because the tile had the exact same shape and size of that cover. Bizarre.

By the way, it occured to me that I also have face blindness. I haven't mentioned it before because I didn't think there could be a connection, but maybe there is? For instance, face blind people may often stare at somebody trying to figure out whether they know them or not.

Now, obviously these are not classical symptoms of derealization, but I really have no idea what other forum I could post this on, and these symptoms do feel like an altered reality, just as derealization makes you feel. And I have no luck trying to google these feelings, because they are really so abstract I can only describe them in vague, long sentences.

Another reason to worry is because I started experiencing these symptoms only recently. I've had other derealization symptoms right from the onset of my OCD/anxiety/panic disorders and got used to them. But these are completely new. Can you even develop new derealization symptoms? Is it because I'm stressed and anxious all the time? Or are these signs of another mental disorder or maybe even a physical condition? I have severe health anxiety, so I can imagine anything from brain tumor to MS.

All replies are helpful! I'm very thankful to everyone trying to help me!