If you were topside during the rough weather it would make a difference.
Often what makes people feel ill is that part of their senses are telling them that they are moving and part of their senses are saying they are not. The conflict produces some motion sickness symptoms.
When on rough water, if you can see outside you have less problems. Its the same with riding. You said you got motion sickness when you were reading, that is when your eyes were not looking out.
