There is no such thing as a negative residual volume (RV) and total lung capacity (TLC) cannot be smaller than forced vital capacity (FVC). TLC can be measured by helium dilution or by plethysmography. Helium dilution can give a falsely low value for TLC if, for any reason, there is any maldistribution of gas within the lungs, or leakage in the system. I would ignore all the lung volume values as they are erroneous.
The most important thing is that you have excellent lung function, based on the large absolute values of FVC and forced expiratory volume after 1 second (FEV1). In addition, the ratio of FEV1/FVC of 72% is right on the money for your age.
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