Bike fit / correct riding position

I regularly get pins and needles/numbness in my left hand when on the hoods for some time.

I know the answer will be "ride in the drops then". But is this likely to be because I'm pitched forward a bit too much and have more weight / too stretched?

Hmm, do you have any history of damage to that hand? Are the left and right sides of the bar/brifter area set up the same? i.e. bar square to wheel, brifters at the same height and both equally straight-ish? Any other asymmetry in your posture? Start with the basics.