I've just completed the Laid to Rest Quest where you have to go to this lair to kill the master vampire that is located northeast of Morthal, and Aela was following at that time as well. So after when i've just got out to Skyrim and went ahead to Whiterun to go to my house, she wasn't there nor the Companions place. I'm married to her btw, Thanks!!

Retrace your steps.I have Brelyna and sometimes she freezes in place.She will look at me but she wont move.

She probaby got stuck in a wall. Youve tried fast-travelling a few times?

I've done that as well too, so i guess i should retrace my steps

Be prepared to reload because even when I find her there is nothing I can do to make her move.

If you're on a PC, you could try opening the console, and typing:

prid 1A697moveto player

That should move her to your location. Not a permanent solution to NPCs getting lost of course, but it has helped me a few times when followers get stuck.

If you're not on a PC, some dungeons have exit tunnels with ledges that the followers refuse to jump down from, and instead get stuck "hesitating". You could check for one of those, and then FUS RO DAH her down from it if she's stuck.