Great post BackPacker
I was once balast weight on a serious aerobatic sortie in a glider, we went from -1.5 to +4.5, everything that we did prior was fine including inverted flight but this maneuver had me laying on the grass in the shade for a good part of the day.
With practice we could get to (briefly) +7 G's without passing out but vision would be completely gone. Never did develop a taste for negative maneuvers.
Hate them to this day.
As to the original poster;
Did you try the steep turns at the beginning or the end of your flights?
If it was at the end of your flights you may have been fatigued already.
Flight training at this stage of the. game is very exhausting, mentally and physically.
It is not unusual for an instructor to not recognize these symptoms and make the training flights too long.