I think she's moreso coming to the realization that she's the only "normal" Stark left and she's probably got a bit of envy in her because from her POV it LOOKS like Arya, Bran, and Jon have been off having cool adventures and learning to be badasses when in reality they've ALL suffered and sacrificed for whatever they've gained.
She was probably looking down like "I got my p*ssy fileted by a madman while SHES been off learning Karate and shyt
"
i dont think she interprets it as them having been on cool adventures. but i think you're right. whatever happened, they all came back different and powerful. she hasn't found her strength yet. still the same old sansa. and being confronted with the strength of her siblings, she's feeling hella insecure about it.
she immediately tried to pull out the big sis/little sis dynamic with arya: telling her she had to call her lady stark, gently admonishing her for "running away from the guards", and laughing at her when arya told her about the list, on some "yeah, right" shyt.
then she found out the list was real.
then she found out arya was real. and not much of a "little" sister at all.
also... imagine all she went through with ramsay, then watching her little sister beat her sworn protector in combat. arya wouldnt have needed jon, littlefinger and the vale to deal with the bolton's, but sansa couldnt have done it any other way.
if sansa is "you can't protect me, no one can", arya is "i wont need to protect you. im going to murder everyone who did wrong by our family". and she can do it. realizing that has gotta hurt for sansa.
that said, i think we're being shown hints that sansa's strength lies in ruling. she's lowkey doing a good job with it so far.