My P/L column is based on a keeping an average position (basis) for all trades, so after 4 short trades ( 1089, 1104, 1107, 1121.75) the overall short position basis was 1105 - if you close out 2 units @ 1116.75 the loss is ~22 (1116.75-1105 x 2)
Nitro appears to be tracking each trade...