I see... I was trying to get 5% on each side (so, effectively 10%) so I will change that for the next tests.
In your GS example, 19.95+19.00=3,895 (not 2,895) so 5% ~ 1.94 so I will target ~.95 per side.
Also, for your Sep4 buyback, I believe that price should have been 6.10 to buy-back the short put, not 3.10. On 9/22 GS was 93.98, so the 100 Put had to be at least 6.00.