Where does ~다가 ~ fit with ~(으)면서 ~ and ~고 나서

[norepeat]

Here's what I know so far:

~고 나서 ~ is used for two sequential actions (then):
저 는 수영을 하고 나서 샤워를 해요.
I go swimming, then take a shower.

~(으)면서 ~ is used for two simultaneous actions (while):
저는 아침에 뉴스를 보면서 아침밥을 먹어요.
I watch the news while eating breakfast.

I've seen ~다가 ~ used to temporally link two verbs as well, but am not sure where it fits into the limits above. For example:
샤워하다가 전화를 받았어요.
Would suggest that it's the same as ~고 나서 ~. Is there some additional meaning I'm missing?

[javiskefka]

The -다가 ending means that the first action is not yet completed when the second one happens.

For example,
오늘 아침에 출근하다가 10년만에 본 친구를 만났어요.
I was going to work this morning, when I met a friend I hadn't seen for 10 years.

아빠한테 화가 났다가 참았어.
I was getting angry at Dad, but I held it in.

[norepeat]

Ah, that makes sense now. I was having a hard time looking at examples and trying to figure out how they were different. Thanks for the reply!