I don’t want to be discouraging or negative, but some people are just not aeronautically adaptable.
I’m not saying you are or are not, just that while it is possible to lessen the discomfort with repetition, medication, and techniques such as looking at the horizon, extreme sensitivity as you describe in mostly 1g level flight may prove insurmountable. At some point besides rendering a normally enjoyable experience unpleasant, debilitating motion sickness (such as throwing up) can hinder performance and become a safety concern.
30 hours isn’t a lot, so keep trying and perhaps you can overcome it, but be realistic in evaluating your chances and reasons why you are choosing to do this.
Good luck!