SJS, I disagree with you on this one:
“It has been my experience that the people who try to be extra machmir during shiva and aveilut are usually the ones who harbor a lot of guilt. Like, they lacked a good relationship with their parent so they are trying to make up for it.”
When my father a”h died I was careful not to listen to music, even recorded music. This wasn’t because our relationship was poor, but rather because that was how he would have behaved (and how he did behave when his own father died). He wouldn’t have thought about how the restrictions of availus made him “miss out on things”; as a true yarai shamayim, shemiras hamitzvos came first. Following the hilchos availus wasn’t so much “a last chance to do something for him”, but rather an opportunity to honor his memory by showing I’d internalized the lessons he taught me.
I didn’t say kaddish, though my brothers did.
I’m not trying to discount your own experiences, just offering a different perspective.