You are better off just looking at the shadows on your negative. The denser values are going to be affected by your development as much as the exposure, so don't look there.
In your negative, as posted, the negative is clear where you would probably like to see some detail. For example under the neck, the eye sockets and the pants are all clear and this indicates not enough exposure. I do agree that it is underexposed, but when you check a negative for exposure, be sure to look in the right places and the negative is your best indicator.
Leaf shutters in general run slow, especially old ones [and this would produce over exposure]. I suspect your under exposure is from not rating the film optimally. Half the ISO for your exposure index and repeat. I'll bet the results will be better.