Originally Posted by RNAV

In my unprofessional opinion, it sounds like your arms/hands are bearing too much weight -- numbness is a typical indicator of this.

A good test that I got from a great fitter was to put your bike on the trainer, and ride in the drops at about 80% effort. You should be able to then remove your hands from the drops and place them behind your back, and just barely be able to maintain the same position without falling forward, and without rounding your back to hold yourself there. If you can't do that, then your saddle is too close, which means your upper body is supporting too much of your weight and you need to shift your center of gravity back some.

If you don't have a trainer, you could try tilting your saddle up slightly, or moving your saddle further back (i.e. increasing your setback) and see if that helps your arms feel like they're bearing less weight. Just understand that with most saddles, if you increase your setback, you need to lower your saddle to compensate for the increased distance from the pedals.