The following lines come from a manga I'm reading. The male lead is a high schooler who uses a lot of truncated colloquial forms. He says the following lines, ruminating on an event where he should have stood up for his girl, but didn't, yet she doesn't appear to hold it against him.
何ちょっとホッとしてんだ
さっき
一歩も動けなかったくせに
The first part of the first line, 何ちょっと, is what's throwing me. The rest is fine. It seems like there's a particle omitted after 何 but I'm not certain.
My main question is, how do I unpack this sentence to make sense of it? And more generally, what are some strategies for figuring out what particle (or other parts of speech or morae)is being omitted in this kind of colloquial speech?
