Message for the OP.
Stick with it. It will get better and considerably so when you are at the controls. I went through hell on my military elementary flying training where Aerobatics are part of the syllabus. When the instructor was flying I felt sick, tired, dizzy etc. After a few flights and getting myself some motion sickness wristbands (from Boots etc) I was much better and when I was poling the AC had very little problem (good job too as part of the syllabus was solo aerobatics - ahhh those were the days!!).
Don't let a silly thing like this ruin your enjoyment, ask the instructor to demonstrate a couple of max rate turns on the buffet. Do those for a while and concentrate on staying focussed, loooking at a point over the nose on the horizon. After a while a normal steep turn will feel like nothing!
Cheers
