You need to put a bit more yourself into it, youre doing what I call: "Faux shouting". Its what many newcomers to voice acting do so dont feel bad. Its when you contain your shout and do a pretend shout in an attempt to not be too loud or something. You need to be that character, at least for those few lines. As far as your interpretation goes, you have something here, you have a good idea of how he should sound, just lean into it more