SUBREDDIT: r/relationships
TITLE: I (23F) don't know how to deal with normal couple things like conflict resolution with my (21M) boyfriend.
POST: I'm with a great guy and we've been together about a year. I haven't been this happy with someone in a very long time. We gel. 

But he.. does things. He might say something painfully insensitive, or leave his underwear on the floor in the bathroom, or spit nasty loogies (is there even a correct spelling for this?) in my sink.

I'm fairly passive and don't like conflict by nature, so I when I feel myself boiling over, I retreat and then bring it up jokingly days later when I've relaxed in a "oh ha remember that one time when I was pissed the f off at ____?.. oh you didn't know?" kind of way. 

Those days inbetween are killer though, because I'm a nightmare where I'm mad but I won't say why. Mostly because I just don't have the language to express it.
TL;DR: 
Where is the line between expressing needs and nagging? How do you say "Hey that hurt my feelings?" or "You do this really annoying thing" without ... sounding like you're bitching?